CKDS Domain Listings.
Here you will find a list of all the domain providers and a brief description of there services.
Easily provide Domain names and Web Space. Easily domain names are what I have found to be the cheapest on the net.
As well as all there other tools Bravenet do sell domain names.
This firm obviously specializes in .TV domain names.
A budget domain name and hosting site based in the USA.
dotFM - Get A Great Sounding Web Address!
.FM are another firm that specialize in a specific type of domain name, I believe you only really want them for online radio stations
domain maniac are a firm that specializes in both cheap and bulk domain names.