Domains
Buy .com, .net, .co.uk and other domain names from registrars or in auctions, get domain appraisals and discuss their values.
NameCheap
Simple and slick user interface and some of the cheapest domain registration prices makes NameCheap a good and popular option as a domain registrar
GoDaddy
The largest domain registrar in the world offering an easy interface and cheap domain prices
DN Forum
Discuss domains and registrars, get domain appraisals and buy and sell valuable domains.