Maybe not pertinent to this thread, but a good tip Ironoggin gave once in regard to freezing crab was to put crab into boiling water until the shell just turns pink (probably a minute or less), drag it out and put it into an ice bath (lots of ice in cold water) to stop the cooking immediately, then freeze in a ziploc with heavily salted water.
When you are ready to cook them the second time, simply finish cooking as you normally would. I must say, it worked like a charm, and the crab tasted very fresh. When I did it, I left them in halves which is decent for a side dish for one person (to kill them, I have a big old butcher knife, and I flip them on their back and cut them in half in one fell swoop).
The quick "flash" boil frees up the meat from the shell so it doesn't stick on the second go around, and like FM said, I like to kill and clean the crab first, then I just steam them for about 10 minutes or so. I find that when you boil them whole, the meat inside the shell gets boiled with the guts and has a greenish tinge to it that I don't care for. Also, especially if you are doing them up on a boat or beach, it takes just a few minutes to get an inch of water boiling versus a whole pot. I use one of those steamer inserts that just sort of butterflies open, and it works in small or large pots.
Man, do I love fresh Dungies!!!!