Check out Threadless tees to find cool t-shirts and order stuff online. Even better... have a t-shirt design in mind? Want to submit it and see what people think (and make a little cash), or rate other people's designs... Threadless allows you to be a designer and artist.... even if you're not (: Threadless is working with artists all over the world to produce amazing t-shirt designs for all of us to enjoy.
Rate some of the designs here:
http://www.threadless.com/submissions
Submit your own:
http://www.threadless.com/submit
Or just buy buy and buy:
http://www.threadless.com/
They update their selection weekly so keep checking them out!