hey sigep:
I hate to bring up the name, but check out Greek 101. They have A LOT of screen printing ideas.
Also, the sig eps on our campus have some pretty neat ideas. This shirt I will never forget. Based on the 7 Up ad... they all wore green shirts and on the front it said "Make Sig" and on the back it said "Ep Yours." And then something about rush 2000 or something. check out
www.sigepcsus.com. The guys are cool so you can probably leave them a message on their guestbook and they would respond.
Hope that helps.
PM me if you need more ideas.