Craiglook is a useful mash-up, which uses Yahoo Pipes to aggregate RSS Feeds from Craigslist and Google Maps to create a new-and-improved Craigslist search facility. Filtering products by location, category, cost and relevance is much easier compared to the original, not to mention the enhanced visual appeal. Check it out!
name your item and it finds items for sale that match your search on craigslist, ebay, amazon and other auction and classifieds sites. Pretty useful and impressive.