I've just released Niche Laboratory Pro 2.4.
The big change in this version is that there's now the option to show a report of expired domains.
How well this report works will depend on your niche. But I did a test job in one of my own niches this morning and two out of the 3 expired domains it showed me were really awesome! And I could buy each of them for around $10 on NameCheap.
This feature is so useful I'm only making it available to Platinum Membership Plan users.
PUBLIC SERVICE ANNOUNCEMENT
Niche Laboratory Lite (the free web version here) is not finding that many keywords due to GoDaddy issues. Until I get them to resolve it you'll not get many keywords out of Niche Laboratory Lite. If you're serious about keyword research then download Niche Laboratory Pro.
Want to find long tail keywords? This awesome keyword tool will find phrases like buy to let to family and how to build a large authority website.