NameCheap.com is a reputable domain registrar. I have assured in it while I reged my domains with them. That process was flawless and quick. And their tech staff worked out professionally.

Name.Com they give free private whois services as well.

No matter what you do, DO NOT use Network Solutions and MAYBE also GoDaddy, have heard rumors about them, try read these:

http://kevinboss.net/website-design/...n-is-available
http://blog.domaintools.com/2008/01/...eas-confirmed/

I would have recommended 1and1, but there are two things stopping me.
1. is that their control panel is very very very very slow, I am not kidding. I once was so close to throw my laptop out of the window, because of 1and1.

2. is that they do not allow bulk actions, so if you are planning to buy more then 1-5 domains, then just think of that you have to change f.ex. the nameservers one at a time! yep I had once around 60 domains at them, it was hell to change the nameservers for the domains.

Good luck and best regards,