I vote for both big bang and reverse big bang, and for the exquisite corpse, because it sounds kind of like pchat, except weirder, and I'm fascinated to see what it would produce. And also for podfic.

Discussion posts sound like a good idea as well. Didn't someone in the comments of tsukinofaerii's canon post suggest doing a "supporting characters of CA, IM, and the Avengers" series of posts similar to the female characters ones?