Instant Domain Search is a great, simple Ajax tool for finding available .com and .net domain names.
Enter a desired domain, and results appear instantly as you type. There are links to Yahoo and Register.com if a domain is available and you’d like to register it. If the domain is not available there are links to the whois registration information.
This is a useful and timesaving tool for people who buy a lot of domains. One thing I’d like to see is a backorder link for domains that are already registered.