Is there a social networking site that links every single other?

[mc_hammark]

And if not do you think it would be a good idea?

For example, you sign up for this one social networking site and it link up everything you are a member of, facebook, twitter, youtube, flicker, tumblr, every single email account you've got, and you can switch between them all with one click. Which would make it much easier for people who have several accounts on certain networking sites, or even emails. I know that hotmail only allows four/five emails to be linked together to easily switch between them, and other than that you have to log out to access the rest.

So do you think you'd use a site like that? One log in and you're automatically able to access every single email account, youtube, twitter, facebook, and nearly every kind of site you could use? Would you sign up and use it?
And also, it allows you to easily find other people who are on different sites because it links up your email addresses to them.

Cause it would be especially handy if you were on a public computer. That way you would only have to remember to log out of one site, instead of four or five you might log into.