CityList. com - Pulls millions of ads from thousands of sites, and then uses it's search algorithm to help you find what you need.
Edgeio.com - A classified listing aggregator that pulls listings from numerous sources.
GoSasa.com - This engine searches hundreds of sites for you so you don't have to check multiple sites.
Oodle.com - An aggregator from over 75,000 classified ad sources.
Vast.com - Millions of classifieds from 70,000+ sources aggregated in one convenient location.
CollegeMedium.com - Allows you to target your classifieds to the universities of your choice.
DormItem.com - College specific classified site that allows you to search listings across hundreds of schools.
InCampus.com - Classifieds for items for sale and events by University.
Adflakes.com - Classified listing sites for eight countries.
Adhysteria.com - Post your classifieds for free with video and Google Map support.
Backpage.com - Free classified listing broken down by metropolitan areas.
Craigslist.org - The infamous Craigslist that just about everyone uses for something nowadays.
EPage.com - Been serving up free classifieds online since 1994.
Facebook Marketplace - We do just about everything else on Facebook, so there's no reason we shouldn't also buy and sell stuff.
FindIt.com.au - A classified site for Australia.
GoForAds.com - Post and search free classified ads.
Google Base - Put up your listing and get indexed by Google.
Gumtree.com - A London specific classified site.
IQZone.com - A classified listing site that allows you to upload listings directly from your camera phone.
MySpace Classifieds - Though many people tend to forget about MySpace lately, it is still the #1 social network based on traffic. As long as you're there, spreading out yet another meme, you might as well stop by their classifieds to buy and sell some items.
Oddbark.com - Classifieds with voice support and a community aspect.
Ollo.com - Search their classifieds different parameters, list your own text ads or full classifieds.
PostPin.com - Some unique features in this one where you can take notes on each listing. Posting is free except for featured listings which are $9.95.
SimpleAd.com - A simplistic classified site broken down by state.
Windows Live Explorer - Harness the power of Windows Live with free classified listings.
Yahoo Classifieds - They no longer have â€œFor Saleâ€ and â€œPetsâ€ sections, but can still be used for real estate, personals, and tickets.
iMoondo.com - Video classifieds that believe â€œwhat you see is what you get.â€
RealPeopleRealStuff.com - Post videos of your items so people get the best descriptions possible. (via)