If you digg, flickr, youtube, etc., and want to have a single profile to share with friends, check out Iminta.com. Now, keeping up with all of your friends' accounts is much easier.
Whatever you do on your social network sites, your iminta profile is automatically updated. You can collect your profiles from other sites as a single feed, or break it up to determine who sees what. This variable approach to privacy is novel, and worth keeping an eye on
The site is now a private beta, but you can request an invitation to try it out.