theres an app called aquarium. all it is is a little cartoon fish that you feed. its prettty unrealistic and doesnt even do anything unless you feed the fish. what if there was a full aquarium for the ipod touch? It could be kinda like one of those interactive windows screensavers. with realistic graphics and fish and maybe some interaction (although I've sat there for hours watching my screensaver) shouldnt be too hard, although if there WAS interaction it would be harder.