Mac users with multiple Finder windows littering your desktop: hold down the Option key when you click on the close button on one to close them all in one shot. This works for any multi-window Mac app (though normally you'd just hit Cmd+Q to quit entirely). Here are a few more things you didn't know you can do on your Mac.

As Windows user, one of the strangest things about Mac OS is a running, active application can be in focus without any actual windows open. If you use Command+Tab to switch between apps and don't want to get stuck in no-open-window limbo, use the following key sequence to open a new window on your way there: Hold down Command+Tab, then press Option, then release Command. It doesn't work for all applications, but it does for Safari and Terminal at least.

Reader Brett writes in with his favourite Safari tip, harnessing the power of Google and keyword search tool Keywurl into one nifty time-saver. He sets his default Keywurl search to a URL that pulls up Google's first "I'm feeling lucky" result, using this string:

Mac OS X Leopard only: Reader Ben points out that there's a lot more to Mac OS X's built-in Dictionary than definitions. He writes in:I just noticed that in Dictionary.app (at least in Leopard), under to "Go" menu, there is an option labelled "Front/Back Matter." Clicking this brings up a whole slew of useful reference material, including a language guide (complete with a list of clichés to avoid), a list of the chemical elements, and the text of the Constitution. Next time I'm on a place, I think I'm going to brush up on the Bill of Rights. It's true: the Ready Reference area of Dictionary.app's Front/Back Matter is a treasure trove of good stuff for writers or anyone who wants to see if they can name the capital of all fifty states in the U.S. Thanks, Ben!

Mac guy Rob Griffiths points out a few brand new command line utilities in Leopard, like the handy dot_clean command, which sweeps away Mac system files that start with a dot and annoy the hell out of you when you use that thumb drive on your PC. Griffiths writes: Prior to 10.5, you had to manually delete them on the other system, or use Terminal trickery to remove them on the Mac prior to copying. As of 10.5, though, you can just use the dot_clean command on the directory in question. Type dot_clean /path/folder to join the dot-underscore files with their parent files. Read OS X 10.5's manual pages (man dot_clean) for more information. Now you don't have to disable .DS_Store file creation entirely; though you may still have to deal with Windows' annoying Thumbs.db system files on your Mac. Leopard's Unix tricks

When you just can't seem to hunt down that file you know you've got stowed away somewhere on your Mac, it's time to break out the Spotlight big guns—advanced search operators, that is. Macworld runs down advanced Spotlight operators which will be familiar to power Google searchers. Here's a sampling: Enclose phrases in quotes, like "time machine" Use AND, OR, and NOT to narrow or widen your search, like java NOT coffee or invoice OR bonus Search by document attributes using operators like author:authorname, kind:pdf (for PDF files), and date:today What's your favourite Spotlight operator? Give it up in the comments. Create good queries in Spotlight

All-things-Mac web site Mac OS X Hints discusses how to automatically Quick Look certain files as soon as they're downloaded to your Downloads folder. The best approach from the thread involves setting your browser to automatically open certain file types (like your PDF or Word documents) with the Quick Look Droplet, a simple application that launches a Quick Look preview of whatever file it opens. Of course you could just set your browser to automatically open downloaded files with their default applications, but if you don't want to load up heavy software like Microsoft Word just to peek at the file's contents, this Quick Look Droplet might be a worthwhile solution. 10.5: Automatically Quick Look certain downloaded files

The Mac Tipper blog sings the praises of Finder's column view, and schools the rest of us on how to navigate files and folders in a flash using the keyboard. Hit the play button to see it in action. How to Quickly Navigate Column View

Tech blogger Dan Warne notes that MacBooks loaded with serious memory—like MacBook Pros with more than 2 GB—can take a long while to activate these days, since the entirety of that memory is being written to your hard disk in the default "safe sleep." If you're almost always plugged into a wall socket or aren't the type to run your battery down entirely, Warne recomments a one-line Terminal hack that brings back the old swift-moving sleep:

Macworld's running a fantastic "Leopard Survival Guide" series, covering little-known Mac tips of all sorts, like how to customise the welcome text in a new Terminal window: Open Terminal and enter cd /etc, press return, and then type sudo pico motd. That second command launches a text editor and loads a new file called motd (Message Of The Day). Type whatever you like for a message (for instance, "Welcome to the land where text is king"), press control-X (for Exit), press Y (for Yes, to save changes), and then press return (to accept the file name, which will be shown as motd). From now on, new Terminal windows will display your new greeting, right below the date and time of the last login. Don't miss the rest of the series, which also covers the Dock and Stacks to Spaces, Expose and the Dashboard. Leopard Survival Guide: System Preferences, Terminal

As the amount of memory in Mac notebooks has grown, it takes longer to put them to sleep because OS X defaults to writing the entire contents of memory to disk before going to sleep. APC magazine Web Editor Dan Warne offers up two ideas for solving the slow-to-sleep problem:You can disable the safe sleep mode by opening the terminal and typing:
sudo pmset -a hibernatemode 0

And to get safe sleep mode back, change the "0" to a "3".

Another option is to use freeware app Smartsleep, a preference pane which gives you the option of letting your notebook just sleep when the battery is close to fully charged, or if the battery level drops below a certain point it will switch to sleep and hibernate. As Dan says, if you usually work with your Macbook plugged into a powerpoint, this is ideal.

How to turn off slow sleep/hibernate mode on a Macbook Pro

Quick Mac tip: If you're even a semi-regular Dashboard user, you've probably been irritated by the three-step process involved in removing a widget from Dashboard: You click the plus (+) sign in the corner, which brings up an "X" on all the widgets, you click the "X" to close the widget, and then you click the plus sign again to return things to normal. Annoying, yes? Weblog TUAW points out a simple trick to prevent this Dashboard annoyance: Just hold down your Option key when you hover over the widget you want to close. The "X" button appears, you click it, hassle averted. This quick turnaround is especially handy if you use multiple versions of expiring widgets, like the most excellent Delivery Status widget. Mac 101: faster widget management

Wired magazine's How-To Wiki covers the step-by-step for duplicating a video DVD using free and pay-for software. They recommend using Mac The Ripper to rip the DVD (sans copy protection) to your hard drive. (We also like Drive-in.) From there, you've got to purchase something like Roxio Popcorn or Toast to burn a DVD player-friendly copy; alternately, make it iPod/media center-playable using the free, open source LH favorite, Handbrake. How do you back up and copy your DVDs? Let us know in the comments. Burn a DVD on Your Mac

Mac OS X Leopard only: Dig into advanced user settings on your Mac by Ctrl+clicking on an account name in the System Preferences>Accounts area. There you can change Leopard's default login shell, the account's home directory or short name, and other important, scary, things that are just daring you to mess with them. (Actually, don't, unless you really know what you're doing.) As for shell options? Mac OS Hints explains: In the resulting Advanced Options screen, either type in the path to your preferred shell, or choose among the various shells already installed in /bin: bash, tcsh, sh, csh, zsh, or ksh. Do you prefer an alternative shell on your Mac? Why? Tell us in the comments. Change your login shell in Leopard

Tech blogger Phil Windley grew tired of trying to eject his external back up disk, first the suggested Apple+E way and then by yanking a cord, just to see that ominous red stop sign of warning every day, even when he knew his disk operations were (or should have been, at least) done. His suggestion for others suffering from clingy back up drives: Parse together a terminal command similar to the one below (substituting name and other portions for whatever fits your system):

Mac OS X Leopard only: If you've got a FireWire drive hooked up to your Mac, chances are Leopard's dead simple backup utility, Time Machine, has you backing up your data—and that's a huge step forward if you weren't backing up at all pre-Leopard. But Time Machine is only one piece of a full backup scheme. Macworld runs down what Time Machine can do (effortless, regular, intervention-less local backups) and what it can't (system clones and online backup). If you want to complete your backup scheme, use an online service (Mozy Home Unlimited is the best 5 bucks I spend per month) and once in awhile, mirror your entire system to a bootable drive. That way if your FireWire drive gets stolen or dies, or your whole system crashes, you'll be up and running instantaneously. What other backup services do you use in addition to Time Machine? Tell us in the comments. Is Time Machine all you need?

Mac OS X Leopard only: You wouldn't think that Leopard's new Quick Look feature would work anywhere but from Finder, but you'd be wrong. From the command line in Terminal, you can invoke Quick Look to preview the contents of a file. Tips web site Mac OS X Hints details how: the command is qlmanage -p somefile where somefile is your document. As Mac OS X Hints recommends, setting up an alias (qlf, perhaps?) is a good way to save your typing fingers when reusing this technique. Use Quick Look from Terminal

Mac OS X Leopard only: Why would you start a filename with spaces? To make it appear at the top of the list in Finder when you sort by name, that's why. Macworld's Rob Griffiths has been using this trick for a while now, and would hit the spacebar to select the files named that way. But in Leopard, the spacebar invokes Quick Look. His workaround: hold down the Option key, then hit the spacebar to select the space-starting file at the top of the list. Good to know.
File selection tricks for Leopard

Hold the Option key during OS X's boot to run the Startup Manager, a graphical tool from which you can select the volume you want to boot. If you're a Boot Camp user, you can choose Windows from here, but you can also boot from external hard drives, thumb drives (perfect for installing Leopard from a disk image), or even network drives. In general you don't need to do anything fancy to boot your Mac beyond pressing the power button, but there's a lot you can do during with OS X's advanced boot options (e.g., earlier today we discussed putting your Mac into target disk mode). You may not use these everyday, but knowing your startup options can come in very handy at the right time.
Startup key combinations for Intel-based Macs