Kingdoms at War is a pretty nice game for the iOS devices (iPhone, iPad and iPod Touch). This game is absolutely free and is a clone of Facebook app called Castle Age with hint of AOE. In the game, you make cities and buildings; attack people to gain their land and thus expand your kingdom.
There is no bank in the game, so you cannot hide your money. So, someone can ‘steal’ your gold if you are not careful. The game is nice filler until Microsoft releases AOE for iPad and other iOS devices.