We now have an entire page of 2k users, followed by a page of 1k users, so hopefully are hitting the right success/size metrics. Traditionally Stack Exchange reward this with a cool swag giveaway. We really need to think about what this could be.
Obviously T-shirts are a no brainer. I haven't yet seen them in person, but @Jeff says they look grand - @Jin's design works.
So what else do we think we would like? One idea per answer, and vote for ones you like.
SE folks - let us know if we are on the right track here and what you have already planned :-)