I'm surprised there is no thread on this great little app yet.
Hotel Tonight - Book a Hotel Tonight
I'm hooked, and use it constantly when I'm traveling. Maybe not quite as good as some crew rates out there, but still pretty handy, especially for last minute non rev, or getting stuck in a city.
It will only show a small number of hotels in an area, but they are usually substantially cheaper than any other search I try.
Download, and make an account using code: DONKERSLOOT1 ($25 off first hotel booking). If you provide an honest review after your stay, they will sometimes toss extra $$ credit to your account too.
It's also not a bad tool for a quick shortlist of good hotels in a city if you are looking to book in advance and have no knowledge of the area.