Maybe you've got accounts at several social media sites, like: Plaxo, LinkedIn, Blogger, Facebook, Twitter.
Wouldn't it be easier to post once and have all these sites updated?
If that's appealing then browse over to ping.fm and check out their free service that does just that for you. I have no idea what their business model is and I suspect that they won't be in business in two years, but hey, it works and it's free. Two of my favorite things on the web.
Since I first wrote this blog ping.fm has been bought by seesmic, then bought by hootsuite.