Web site Crazedlist performs multi-city searches for Craigslist posts across the US or the world, and once you put together a perfect search, it makes it all available via RSS.

Free Craigslist mashup webapp CLhack puts a tabbed, picture-oriented interface on the free classified ads page, offering a visual alternative to clicking through deals based on over-used, all-caps adjectives. Keep the "has picture" option checked, set a minimum and maximum price, and click on any image result to see the full set of product images and the actual listing text, similar to hardware e-tailer NewEgg. It's a super-useful hack for those looking for computers, cars, apartments, or anything else for which a visual preview is mandatory. CLhack may not, as TechCrunch notes, stick around forever, but for the time being, it's a cool Craigslist front-end.

CLhack

Don't toss that CD you don't need anymore—swap it for something else you've been eyeing with social swapping site Commuto. Find goods you want at Commuto and set up in-person sales (should money be requested) or face-to-face swaps with the member who's offering what you want. Commuto offers a large database of items to choose from, and it will match up the UPC symbol or ISBN with the title of the product if it can locate it. You can also create a wishlist for prospective swappers. Like Craigslist, Commuto takes no commissions. Currently, Commuto is in beta with small but growing communities, and it looks promising, especially if the sheer size of Craigslist is overwhelming. Commuto

Wired's How-To Wiki details how to flex your Google-fu to get Craigslist results from every Craigslist domain. In essence, the author does a Google site search of Craigslist.org and excludes pages with the word 'directory' to eliminate directory listings of names and phone numbers. The resulting query looks like:

Reader Paul writes in with a handy Craiglist searching tip: Contrary to popular belief, Craigslist does have an Boolean "OR" search method; it can be done by placing an apostrophe just before each search term. I discovered this by the trial and error method. By default, Craigslist uses a Boolean AND between search terms; for example, searching the Seattle Craigslist for an ad containing the words Blue AND Green AND Red AND Orange you would simply enter: Blue Green Red Orange in the search window, and get about 43 results, each containing all four words.

Firefox only (Windows/Mac/Linux): Firefox extension Craigslist Image Preview adds a thumbnail of the image(s) within a listing on Craigslist without requiring you to click through to the actual page. Since most Craigslist ads live or die by the included image of what's actually being sold, this extension saves a ton of time and is a must-have for any Craigslist shopper. Craigslist Image Preview is free, fast, and works wherever Firefox does.

AU - yes, there is a Craigslist for Australia, well Sydney at least.

Fancy-pants dynamic web site crgslst searches multiple craigslist cities on a single page (but not at the same time.) Crgslist can save your cities of interest and past searches for easy reuse, too.

AU - Craigslist isn't Oz-wide but does cover Sydney.

Craft your eBay or Craigslist advertisements for people who are likely to misspell words or find great deals on expensive items by capitalising on sellers' misspellings. TypoBuddy is a website that performs a variety of searches on both eBay and Craigslist based on all possible spelling combinations and makes it easy for you to dig for great discounts. The simple search will show nearly every misspelling in the alphabet, but if you drill down to the Advanced search, you'll be able to fine-tune your searches to include typos with numbers and/or to exclude search terms of your choosing. You can also narrow down your search to specific price ranges or view listings on Craigslist that have pictures only (or Buy it Now! items on eBay). If you're in desperate need for a product and are looking to save big, TypoBuddy should be your first stop. TypoBuddy

Craigslist is an excellent tool for finding great deals, but if you're trying to put together streamlined Craigslist searches and feeds to stay abreast of a specific set of results, it can be difficult to build queries beyond very basic, inflexible keyword searches. For example, Craigslist search does not support wildcards, nor does it support AND, OR, or NOT searches. To make more useful Craigslist searches, the Witigonen weblog uses a combination of Yahoo Pipes with Craigslist to add all of the missing advanced search capabilities to Craigslist—and remove frequently occurring items. Whether you're using Craigslist to keep track of job postings or hunt for a great new couch in your area, a precision search can make the difference between finding what you want and getting buried by what you don't.

How to Actually Search Craigslist