Hey guys - I replied above (http://news.ycombinator.com/item?id=5173296) but the short story is that until quite recently we didn't have enough traffic to really help organizers sell their tees, and didn't want to imply that we did by offering a marketplace.

We also didn't have a huge amount of cool campaigns at any one time (up until recently) - which would have made for a pretty poor browsing experience!

We're working on expanding our discovery tools, as wiwillia explained above, but any discovery tools will always be filtered, either manually, or by fairly stringent criteria, such as already having sold a number of shirts. As with any website that freely accepts user-submitted content, making it easily viewable to the public is inviting abusive and spammy submissions.