Interesting thread...
I read over my old stuff fairly often. A lot of it is on my blog, and I like to revise my old work, while trying to remain true to the original spirit of the piece (I keep drafts of the older versions though). I'm currently in the process of putting together my first collection of poetry, so by necessity I'm having to read over and revise a lot of my work. At the moment I've probably got 20 or so poems that I'm happy with, and about the same number of poems that still need substantial editing / rewriting.
As for the really old stuff that I wrote when I was 17-19, most of that is stashed away in folders. It's always an experience pulling that stuff out and reading through it: so much darkness, violence, despair. But also a lot of experimentation and crazy ideas that make me smile.