Re:register.com (Score 1, Insightful)

Register.com has, hands down, the best support I've ever dealt with. They're easy to deal with, knowledgeable and a prompt to take care of any problems I have. They'll even call me before my domains expire if I haven't renewed yet, to be sure that I'm aware that the expiration is approaching. Maybe that's a sales tactic, but it's also pretty helpful when you're managing a large number of domains. Their online management tools are easy to use and work well too (unlike the other registrars I've used).
I've used some of the cheaper registrars and they've all had awful (and slow) support, lots of screwups, etc. You get what you pay for, and I'm happy to pay an extra couple of bucks a year to get the kind of support Register.com has. They're the only one I'll use.