Before the new day dawns and others jumped in, we will make our customary note that we do have a dermatology firm on the WSB sponsor team, Westside Dermatology in The Junction:
http://www.westside-derm.com
We haven’t had occasion to need a dermatologist, so can’t vouch personally for them or anyone else. However, even before we had ANY sponsors (we started running ads in Nov. 2007), they (and others) had positive recs here in threads like this:
Reader recommendation request: Searching for a skin specialist
Good luck!