Triple Clicks is a neat site, much like a virtual garage sale, where you can sell your stuff and buy credits to bid on super cheap auctions.
An all time reliable and easy to use forum where you can buy and sell things at much lower than retail prices! You can filter by city or province to maximize your audience! Best part, it's free!
Another auction site where you can list items/services and have people bid on your unneeded items. They do take a fee for posting though.