I registered for twitter a while ago, tried to force myself to use it for a few days, then gave up as I didn't see the point. I looked at my updates and they were something like:
-is going to work
-is coming home from work
-is babysitting his nephew
etc. I didn't understand who in their right mind would care about that stuff, so I stopped logging in. I have since come to understand twitter.
I started up a tech blog and wordpress has this twitter plugin where you can have it send out a tweet whenever you make a blog post that contains the link to the blog entry. Kinda neat, so I signed up for it under a new account. I got tweetie for my iPod touch and while I was playing with it, I discovered it had two interesting features: A location based search to see the recent tweets from wherever you are, and a topic based search, to find tweets containing a certain word.
I find myself browsing the local tweets quite often. There's quite a bit of interesting stuff going on in the neighbourhood and it's fun to keep up on it.
I also did a few searches for "GMAT" and am now talking with several MBA hopefuls, giving them tips and application essay help. Actually, with the number of people on twitter talking about the GMAT, I've considered offering my essay review services and charging some money for it...