YoName is a service that will find any user on the major social networks.
It looks like your typical search engine start page. Simply type in the first or last name, username or email address of the person you're trying to find, and YoName will scour Facebook, Friendster, MySpace, Xanga, Match.com, LinkedIn and Digg. YoName displays all the results for each social network, though searching myself, YoName only came up with two results. Odd, considering I have an account on four of the social networks they search. Search results include the user photo, location and age, as well as a link to the public URL of the respective social network. If YoName can't find an exact match, they will show all the matches possible.
YoName could be considered a niche search engine that is targeting the social network aggregator crowd. I guess the most useful place for YoName would be within a social network aggregating service, so you can find the users you want to add to your centralized profile location. These would include ProfileFly, 8hands, LinkMyBox and Tabber. YoName won't offer you updates on information and you can't save searches, so don't even think about using this to stalk that girl you have a crush on.