There's some okay designs, but they're all either exactly the same as ones I've seen before, or basically the same idea in a slightly different form.
The site graphics (logo, background) are pretty basic, and the site name didn't make sense to me until I saw it spaced out in your signature.
I think the geek market is going to be a pretty web savvy one. Whereas a Threadless knock-off can hope that some of their customers will wander onto their site before ever seeing Threadless, it's not likely that anyone who would be interested in your site wouldn't be familiar with ThinkGeek or Jinx. So what can you give them that those sites can't?
At the moment you have no point of difference. Well, except for the fact that your site isn't as professional looking, and doesn't inspire the same level of trust in potential customers. I'd punch up the colour pallette a little (nothing gaudy, but something less like a biege box), and come up with some ideas that set you apart from the competition. As a customer, if I wanted a d20, a joystick, a pi joke, and a line about 'my other t-shirt' I'd shop at ThinkGeek before I'd ever purchase from you. So give people a design they can't just buy from The Other Guy and you might be in with more of a chance.
Also, try giving the site some personality. At the moment it makes Mac's vision of a PC look like the life of the party.