Does anyone have any ideas on keeping track of the many people in my life, from central to peripheral, from friends to collaborators?

I'm heading off to grad school next year to continue my training as a cognitive scientist. For the kinds of interdisciplinary research I'm interested in, it's very valuable to meet and converse with other researchers from many disciplines, and maintain those connections over the years.

I've already accumulated a large list of wonderful people I've met in academic settings (classes, conferences, student groups), not to mention other settings.

I'd really like to offload a list of people onto the computer, where it'll be saved more durably than in my brain. And I'd like to have tags or categories or notes too (e.g. "Joe Johnson, met him at X conference, he's at Y University, he does research on Z, and likes to skydive").

The social network websites (e.g. myspace, friendster) are inadequate because everyone has to be a member. Maybe a standard address book program might work? I'm on Mac OS X and the built in one allows for categories and such. Alternately, I was about to just start a braindump text file. But I wanted to see first if anyone knows of any better tools for this kind of task? Thanks