I heard about 99dresses on the podcast, Download This Show. 99 dresses is a mobile app that enables users to swap clothes. You can list the clothes you want to swap and browse the app to swap with others. It is only available on iOS now. Hopefully 99dresses will be on Android soon.
Swapdom is another new swapping website. I heard about this site via a blog post by Kellie. You can list items, search for items you want, offer your stuff in exchange. Swapdom helps to arrange the swap.