LastPass has a similar service for some of the recent (and not so recent) hacks:
* https://lastpass.com/linkedin/
* https://lastpass.com/linkedin/
http://blog.lastpass.com/2012/01/new-years-resolutions-with-...
This demonstrates nicely why that's a bad idea.
How is this possible? How did Adobe leak my address if I don't even have an account?
The LastPass checker is really nice. Whats scary is that it found a few other people that had the same password as me.
For the Adobe breach, LastPass also emails you a sample of the password hints of others -- its kind of funny how people remember a certain string.