Human Shield

Are there any feats out there enabling a character to maintain a grapple with an enemy in order to gain a shield bonus in the midst of a melee?

I'm sure you've all seen it at least once in the movies.

I don't know about any feat that provides a shield bonus from a grappled creature, but I suppose a grappled creature would provide soft cover (+4 vs ranged attacks) just like any other creature that is in the way of a clear shot.