Monster.com has been hacked exposing usernames and passwords:
If you used LastPass and used a generated a password, just login to Monster.com and generate a new one.
If you're part of the majority of the population that uses the same password on every site, you should be worried. Some nefarious characters have your username and password to many of your sites. This is just another concrete example of why your current password management strategy of "none" or "tiered" is a bad idea. Unfortunately this isn't rare, it's the second time it's happened to Monster.com!
Protect yourself -- use a different password on every site with LastPass. Here's the basic instructions on how to use Generated Passwords with LastPass: