Here's a quickie. The beauty of twitter is that by limiting each entry to 140 characters you're forcing creativity. Same reason accomplished artists paint "still life with fruit" over and over again.
How about this...a social network where you have a maximum number of friends. Like 15. And whenever you add another friend, you have to bump one to make room. And just for fun, when you first sign up you are automatically assigned 15 friends based on your interests.
At first, you say "well, that sucks because I would have to pick and choose my friends and people would be insulted."
But I'd bet the dynamic would actually be a lot more fun. More like hanging out with different people on different nights of the week. You could even take it up a notch and have forced rotation Volleyball style; every week you lose a friend and have to pick a new one.
Good idea?
This is Ari Paparo's blog. It generally concerns itself with Internet product development and marketing. 