Hotel Tonite is so convenient; you can do everything on your phone, show up at the hotel and just get your keys at any time!
Priceline will give you info on the hotel including amenities and bed type. They'll also give you the room rate so you don't need to bid.
Priceline's mobile app will help you find a hotel and winning rates in a particular zone.
With Hot Rate hotels you are allowed to see the price and the amenities of a hotel but not the name of the hotel until after you book it.
Quikbook's Secret Sale Hotels is especially good for major cities like New York and Los Angeles.
Travelocity's Top Secret Hotels