dpAutoRigSystem

http://www.creativecrash.com/maya/script/dpautorigsystem

I've used some sweet auto riggers but this one really impresses me. I managed to rig up a simple skeleton character in about an hour - skinned and all. Very user friendly system based on mirrored guides, rig set up and a super fast skinning GUI.

Dig the rig too. Comes with all the treats, stretchy IK, finger set drivens, world head rots etc etc etc