've taken up the tile in my kitchen. I want to just stain the cement floor. I'm having trouble getting the old mortar up. Any suggestions?

How about this?

Concrete Polishing, Diamond Polished Concrete, Stain & Polish Concrete Service, Warehouse Flooring (http://www.yesitsconcrete.com/default.asp)

Actually, you can rent some machines from Home Depot that will remove stuff, but definitely not as spactacular as the above.

Also, not sure if you want to epoxy paint it.