Apple won't release Mac OS X 10.9 Mavericks until later this year. Impatient? You can get many of the best features announced for the next version of the desktop operating system through third party apps and plug-ins right now.
Finder Tabs and Tags
Tabs and tags have been available as a Finder option for years by using alternative apps. Third-party app Pathfinder provides both of those features and many more. It's a file browser for power users, and lets you split windows, open up a terminal window, queue file copies, put folders on top in file lists, and a whole lot more.
If you prefer to stick with the traditional Finder but want to extend its features, get TotalFinder instead. It will add tabs, and you can incorporate tagging separately with an app called TagIt. While neither option will provide the highly integrated user experience you'll get with OS X Mavericks, it should be enough to tide you over.
Multiple Display Enhancements
Apple thankfully addressed many of the annoying multiple display quirks introduced in OS X Lion with the announcement of Mavericks. Unfortunately, no third party app can put two full screen apps side by side.
You can, however, improve your situation with a somewhat pricey app called Multimon ($10.49). It sticks a second (or third) menubar on your other monitors, makes it easy to move windows between each display and resizes them appropriately, and provides customisable hotkeys for quick access to its functions. If you only want multiple menubars, check out the free Secondbar instead.
iCloud Keychain brings password syncing to all your Apple devices, and it will remember credit card numbers, form information and Wi-Fi passwords as well. The downside? You can't sync with non-Apple devices. Fortunately, better solutions exist now. Lastpass does a great job of managing your passwords. If you want those 'eWallet' features you'll want to sign up for Dashlane instead.
You've had the option of adding synchronised notifications for a long time via Lifehacker favourite Growl. Long before Notification Center, Growl handled notifications for apps in exactly the same way as well as working with other apps to snc your notifications across devices. It can take a bit of setup, and it won't work as magically as it potentially will in OS X Mavericks and iOS 7, but you can do it. Check out our guide to consolidating notifications and alerts for Windows or Mac for more information.
Calendars, Maps, iBooks
Calendars is losing its leather look, while Apple had added Maps and iBooks to the crew of included OS X apps. If you want the simpler, leather-less look of Calendars, simply download Lion Tweaks and turn it off. To get maps you can send directly to your iPhone, use Google Maps and push them with an app such as myPhoneDesktop or Send to iPhone.
Lastly, you don't really need iBooks when you already have Amazon Kindle. While that won't help you if you have a bunch of iBooks content already purchased, Kindle users can access their books on virtually any device. If you don't want to lock yourself into the Apple platform, Amazon at least lets you choose your devices.
Of course, OS X Mavericks packs in a bit more than you'll find in this list, but third-party apps can't replicate all of the features (including the secret ones we have yet to discover). Let these tools tide your over for now, and see how well the new options work when OS X 10.9 officially launches.