How long has it been since you took a look at all the apps that have permission to your personal data from all sorts of various networks you are inevitably a part of? I highly suggest taking a few moments with MyPermissions.org and cleaning up who has access to what. Maybe you tried out a site for a test drive and had to give it permission to your information in order to do so - it's high time you revoked that access. My Facebook account was particularly overrun with applications that I don't even remember hearing of but that's likely due to their behemoth size rather than any suspicious activity.

Long story short, take a few minutes and clean up your accounts.