There is a nice little thing that you can do with your Gmail address (only) that can help you find out what sites have been selling your gmail address. Kudos to PCBGuy and the post they made on Hedir Review here. But here is the post if you don’t want to traverse the net to get there:
When you give your email address to a website, you hope that they don’t sell or trade your address to a bunch of spammers. Well if they do, here is a simple way to see what sites are responsible for what particular piece of email. This requires you have a Gmail account.
If your Gmail login name was [email protected] and you went to samplesite.com to fill out a registration form, instead of just entering [email protected] as your email, enter it as [email protected] instead. When Gmail sees a “+” in an email address, it uses all the characters to the left of the plus sign to know who to send it to. In this example it would still send it to [email protected].