I use Enom as a registrar.
They are great as far as I am concerned, and have good customer service.
They also operate their own .com drop catching service and are quite successful in picking up a good proportion (some) of the drops, and compete on a level field with dropcatcher et al.
I imagine for sure that they keep the best ones, but I've had a couple of good .coms on the secondary market from them.
Free to register.
-aqls-