I was looking for a domain name earlier for a niche I'm having some content developed for and thought I'd share my little method for finding available domains real quick. As you know it's a pain in the ass to search for available domains one by one, or even typing them out to do multiple searches at once because there are so many already taken.
1. Since I use google's keyword tool to find keywords for my content, I export the list in .txt format and save it to my computer.
2. I take that list of keywords and open it up in a word processor like textpad, then use the find and replace feature to remove the spaces between any multiple word keyword phrases. (you can also replace the spaces with -'s to separate your keywords)
3. I copy some keywords from the list (usually about 50) and go to 000domains.com or some registrar where you can do a bulk whois lookup. Paste the list into the box, select which domain extension (.com) and hit the button.
4. The whois tool spits out a list of available domains highly specific to your niche. Most will be taken especially if it's a competitive niche but it's bound to turn up a few available.
The whole process takes about 1-3 minutes depending on how long it takes the whois tool to do it's thing.