Just a bit of advice, and I know 99.999% of you already know this, but...
Make sure you buy the domain they will work on, not the other way around. I know far too many people who get burnt by having the designer running the whole show and registering the domains, then all of a sudden dropping of the face of the earth with a 5+ year lock on the domain.
I really like Bluewire Design, Pro Adult Outsourcing, and Insane Adult Creations. All of these companies have been reliable and very talented.