Guys I am saying you can tell me games and apps that you use that don't need root or extra data to be downloaded..
If I understand you correctly, you want apps that don't need data after you download them. Let me know if not.
Angry birds - All of them (I know the games are old, but if you don't have data enabled, all add are disabled)
Audio Manager - It's great for managing audio and has a place to hide pictures, video and apps if you want.
Juice Defender - Has options to restrict your data to save power (and data bandwidth).
Lookout - Has some good security options
Pocket - I'm not sure if this counts, but you can set it up to download articles when you're on wifi and keep them to read later when you don't have connection.
Pac-Man - Pretty fun version. I think it's free in the play store.
Rope Escape - Not a bad game when you have a few minutes and no data.
Swiftkey - I prefer this keyboard to the stock one.
Wave Launcher - Cost a few dollars, but it has a nice and innovative way to switch between your apps. I use this daily.
Hope these help.
NB