There is a site called PwnedList that can check if your email address is contained in public data that has been taken from computers and web sites that have been compromised by hackers. The site started out as a research project to find out how many compromised accounts could be harvested programatically in just a couple of hours.
To use the site all you have to do is put in your email address
To use the site all you have to do is put in your email address