[k33n]

I'm sure you're not the only one who hasn't heard of it until now, but I've been using it for awhile and it's actually pretty useful. I like their topics feature. I can see who the most influential people are in the "startup" topic and immediately start interfacing with them via Twitter.

I'm part of the 50% of Twitter users who are active every day, so I can see why if you're a part of the other 50%, or you just don't use Twitter at all, this wouldn't be very appealing.