On Fri I signed up on Twitter.com. It's a bit of a cross between instant messenging and a blog.
The "breakthrough" is that it can be used via phone (SMS), IM, or the web, and has a decent API.
I've added my Twitter RSS feed to the right side of the website...
I don't see myself updating it nearly as much as I have this weekend, but I'll probably update it more than I do this site.