[grag]

I think halo's critique is pretty much correct. You've done a good job with the site, but I just can't see it gaining any traction against ebay, craigslist, etc.. in it's current form. You've got a lot of nice features, but consider stripping the site down a bit and focusing on a specific niche or interesting concept that is easy to convey. For instance, what if the site was entirely focused on submitting things you want and submitting things you have and it automatically matched up buyers and sellers. Not saying that's a great idea, but it's one example of how you could take one of your concepts and focus on it entirely to begin with. Then as people start to use it you can expand your site and start adding in the other pieces. Anyway, that's what I would consider doing if I were in your shoes. Also, like matt1 said, usability testing and focus groups would be a good idea.