Excellent domain search tool, ajaxified, and supports multiple (even configurable) extensions, probably not 100% reliable though if it relies on whois.
Free domain names (without DNS) on the .za.org and .za.net subdomains. Requests require human approval and so can take a few days. Interface is plain text to email, old school!
A great little tool. Give it a vaguely regex like pattern and it'll give you a list of all the possible words. Want 5 letter words ending in me or be, gotcha! Great for domain name inspiration. Output is scripting friendly plain text. :-)
Wild West Domains is the reseller arm of GoDaddy. Same company (I think) but WWD allows you to setup a whitelabel domain reseller system.
The web 2.0 name generator from dot-o-mator is an interesting tool which generates an endless stream of Web 2.0 sounding names. Useful for name inspiration.
The dot-o-mator allows you to punch in a bunch of keywords (or it has predefined lists) and combine them to make domain names. Then with one click you can check the availability of all those domains. Very useful.
A great tool to search domain names. Type in as many words as you like and the results appear below almost instantly via sweet ajax interface. Very nice.