namecheap.com, best domain name registrar by lifehacker
+1. I've used network solutions and godaddy before, but namecheap has provided the best UI, customer service, and even price. Very tech friendly and very little bait-and-switch popup marketing.
I use godaddy, but I'm not impressed. Just haven't got around to transferring. I would recommend you go with someone else.
I use FastHosts, had no issues and DNS records get updated pretty quickly whenever I make changes.
I really like DNSimple.com. I've been a customer for over a year and highly recommend it.
I've been using Moniker for years and their bulk domain management is solid.
Hover.com and 10dollar.ca.
gkg.net - Reasonably priced, and they support DNSSEC.