I had something similar happen to me. On March 24 I signed up for a T Shirt offer from Funk Unlimited in order to get a free game offered by FreeVideoGames.com.
That very same day, some named "susanmadlinger@yahoo.com" signed me up for the "Best Life Diet" using the Discover Card I had used at the Funk unlimited site.
Shortly afterwards, My personal info and credit card was used to sign me up to the following:
P9*Privacy Matters123
P9*SavingSmart.com
SCH* Scholastic At Home
I contacted FreeVideoGames.com and they indicate that others have had the same issue after purchasing a T shirt from Funk Unlimited.
I had to cancel my Discover and sign up for the 3 credit bureau monitoring just to make sure no one steels my identify.