I really think the stand alone AppleTV could really be Apple's next big thing if they would open it up and create an AppStore for it. Not only would be be nice to have other 3rd party video streaming apps (HBO Go, Amazon) but I could see a big market for games - especially simple family type games where other iOS devices or BT devices could be the controllers. I'm thinking trivia type games, family feud, dictionary etc. I could also see market for video conferencing/viewing (like how apple does their WWDC stream other companies/events could have their own app and stream).
The biggest obstacle with the current release is storage. I believe it only has 8gb which is primarily used for buffering. To allow apps it would take away from that. What I'd like to see is more of a cloud management system were apps could be stored in the cloud but load into memory instead of taking permeant storage space.