Grand Theft Auto 4 (GTA 4)
I think perhaps the coders can utilize the in game cheat system for a trainer. The codes via the cellphone is hard to type in and not useful when you are under fire. If we had a trainer that just typed the cell cheats in for us with one click that would be awesome. This would be useful only for us who don't care about achievements, of course. Just a thought.
Once the cheat is activated for the first time it goes into a Cheats menu where you can instantly activate it. nothing to type in.