I have just ordered niche finder software for low competition niches advice. Its something like keywordtool, but little bit more handy and advance.
Visit NicheFinder website
to view video Niche Finder presentation.
To get domain availability data (last column in software) you need to buy membership there. But i dont think free domain research is crucial part of Niche Finder. If you will be lucky, you may also try Niche Finder discount page for SENuke subscriers, i got sw for around five bucks. nichefinder.bradcallen.com/se-nuke-special/
You also need free Google Adwords account for the software to work.