I signed up to be- and got assigned as- the TopCoder Student Representative to Washington University. My three tubes of posters (that's 29 posters to post, one for me) arrived yesterday. And therefore, if anybody signs up saying they're from Washington University and mentions either my username there (Windrider) or "poster" as the way they heard about the site, I get a T-shirt. One sign-up's all, so I should be able to get that.
I'm aiming for ten, though, because then Washington University will have enough coders to be officially ranked.