I'm getting more and more interested in microblogging. As well as trying out Tumblr, I've also started a Posterous microblog.
There are other sites very much like these that allow you to post different kinds of media, and also have Twitter-like social features.
I've recently found two more. These are Onsugar and Soup. They both look good and as far as I can tell they also have free domain mapping like the sites mentioned above.
UPDATE: Have found the feedback page for Soup, which gives a pretty good idea of what it offers. It's clearly a lot like Tumblr in many ways.
UPDATE: Just found another one: Amplify. It also looks good, with similar features. It doesn't seem to offer domain mapping, however.