If you're one of those people who tries to grab his or her own preferred username on every new service that comes along, just in case the service becomes hot one day and you want to start using that cool ID, check out this new tool: Usernamecheck.
All it does is ask you for a user name, and then pings about 45 services so it can return to you "taken" or "available" for each one.
If a name is taken, it can't tell you if the owner of it is you or someone else (how would it know?), and there's as yet no way to add new sites for it to check--you have to wait for the developer to add them. Also, it's slow. And it doesn't appear to work on anything but Firefox.
But this is a useful tool for managing one's personal brand. And here's a tip for parents-to-be: Run your baby names through it, as well as through BustAName. Your kid might thank you.