Do you know the barter section of Craiglist? If not and you have some old stuff around your house that you'd like to trade out go check it in your area. Even if there is not very much in this Craiglist section maybe you'll got the chance to at least get rid of those old and not so useful things.
But what if you are a student in a campus? Then Bubblevine may help you:
Bubblevine is the place for college students to buy stuff and sell stuff.
According to its creator, entrepreneur Monica Yoo this idea is originated in her own college experience:
While I was a junior in college at Trinity, I was looking for apartment furniture on Craigslist but found that the stuff I needed was all over town, often in sketchy areas that I wasn’t comfortable going to. Meanwhile, college kids were throwing away stuff at semester’s end.Source: Buy & Sell Your Stuff on Campus with Bubblevine
A more generic trading site is Love2trace whose more detailed review can be read on Startup Houston post: Get Your Trade On At Love 2 Trade