One thing I've wondered. Is it possible to follow "everyone" on Twitter? If-not, what type of cap does Twitter enforce on the number of accounts you're allowed to follow? I realize it'd be difficult to know which new accounts to add as people join, but how far could you push a roll-your-own stream of the Twitter firehose?
Hypothetically: I'm sure you could do it algorithmically; if your program sees a retweet from someone who is not on your following list, you then follow them. You might miss a few, but you would get most everyone.
