I've been curious about tumblelogs for a while now; they scratch an itch I have: super quick input of links with commentary. del.icio.us isn't quite for me as it's too focused on network effects and you can't change the look-and-feel. So I'm giving tumblr.com a try over here. If I like it, I'll write a cronjob that posts my tumbles nightly to this blog as a single post.
Let me know what you think.