I've been on Twitter for a while, but only recently started using it in earnest. I've got 'rific, have my Growl notifications up, and run a few Tweetscans through my feed reader to rush to the rescue of JRubyists in trouble. But I try to do something it seems most tweeters don't: I try not to crapflood my followers with useless bullshit.
Don't get me wrong, I'm all for stream-of-consciousness information flow. I do it myself, either when hanging out with people (where it might form the beginning of a conversation) or when on IRC (where it often doesn't, but is easily ignored). But I dunno, it seems to me tweets ought to be something at least a little more substantial.
So I'm keeping my list of followees small and tight. Around 20-25 seems like a pretty good range.
That's meant unfollowing people that tweet nothing but their travel schedules, where in the house they happen to be sitting, what great new product their company just released, and a load of other nonsense. That's meant not following everyone that follows me, especially if their primary topics include walking the dog and taking out the trash. To me, the value of Twitter is both in keeping track of what people I respect are working on or find interesting and as a sort of micro-feed, a little forced 2-second thought break to help me step back from hard problems. Whether you buttered your toast on the bottom or found an unrecognizable lump of once-food in the refrigerator is worthless to me...so if that's the tweets you're inflicting on the world, why should I begin or continue to follow you?
Of course there are a few folks that have a few very insightful tweets sprinkled in with others I don't find interesting...not necessarily a signal-to-noise problem, but a relevant-to-irrelevant thing. It's a judgment call, so if you're not immediately followed by me don't take offense. We just have different interests.