Yeah, you can do this with just about any app using a memory hack. Pretty simple to use. It can be useful for those freemium games. Example dollars vs coins where coins you get all over the place but dollars are hard to come by and that's what you would usually buy through in app purchases.
A memory hack will enable you to change the value of the dollars so you can get whatever you want. But as you stated, it's cheating and will probably ruin the game anyway.
GameCIH is an app I've used before to do this exact thing (Contract Killer, had to get a good gun