Sugar Daddy refers to the club's chairman.
Foreground - Will keep pumping money into the club until he leaves.
Background - Will supply money for 1 or 2 promotions/3 or 4 years.
Underwriter - Will only supply money if the club is in danger of bankruptcy.
Let's get to the list of sugar daddy clubs on Football Manager 2012.
Foreground Sugar Daddy
Background Sugar Daddy
Underwriter Sugar Daddy
Credits to AcidBurn on the official SI forums for this list.