What are some great math social activities for students? I'm looking for things that bring people together with a "light" mathematical touch. The goal is to create a stronger mathematical community in a small college math department.
Examples I've heard so far:
Math Stack Exchange Party: Students get together and surf questions on this site and answer them.
Zome Tool Party: Students get together and make cool things out of Zome tools.
Integration Bee: Spelling bee....but with integrals!
I'm looking for "soft" ways to attract students to the major. Thanks, in advance!