Okay, I'm tooting my own horn here, but a number of people have found it useful enough that I thought it was worthy of mention in this blog.
Duke of URL is a little application that I put together that spits out up to 100 available domain names based on a word or phrase that you provide. The Duke spits out .com domain names by default, but you can also have him give you .net, .org, .info and .biz domains if you prefer.
The Duke is written in PHP (PHP 5, but it's compatible with PHP 4) and makes use of Tucows' OpenSRS API for provisioning and managing domain names. I wrote it to showcase the NAME SUGGEST API call that was recently added to OpenSRS and to demonstrate one possible use. Over the next few weeks, I plan to post the code along with explanatory notes as well as upgrade the Duke to some other possible applications, including mash-ups.
As I mentioned earlier, the Duke generates domain names that are also available. I was under the impression that most of the word-combination domains were taken, but so far the Duke has always been able to provide 100 domain suggestions for every word or phrase I've tried. As usual, there's a lot of junk in the results, but there have also been gems that would have me reaching for my credit card if I were more of a domain speculator. (Maybe I should do that.)
Give it a try!