I don’t have an iPhone (I know; I’m deprived), so I can’t vouch for this brand-new app, but the concept sounds cool. It’s called GenieDS, and for $2.99, you can download the app to your iPhone or iTouch and access tips and (authorized) “cheat” codes for more than 150 games. New codes are added for new games daily, but you don’t need an Internet connection to use the app. There are codes for popular games such as Mario Kart DS, New Super Mario Bros. and Guitar Hero.