My wife and I went to the Maryland Seafood Festival a few weeks ago and had some pretty darned good crabs out there. We found out the place that supplied them was the Kent Island Crab Co in Pasadena.
Bethesda Crab House has been our favorite for a while, but this place gets them from the bay - Bethesda gets them from down south - and man, these crabs were very tasty, meaty and heavy. The dozen mediums felt like a bag of rocks when I picked them up.
The only thing is that it's a carryout place, but they were some of the best crabs we've ever had. I think the mediums were 38 a dozen and they offered deals if you bought two dozen. There's also a Rita's Ices about a block or two from the place.