The music player cube is the most complex app available and it also takes up 6 tags to use. But in return you get a cube that can do about anything iTunes can do. You can assign play controls (like play, stop, next track), music files (that you can stream over the internet) and web radio stations to tikitags. Since a cube has 6 sides there are 6 things your cube can tell iTunes to do by just touching the tikitag reader. The idea is that you stick the 6 tags on the sides of a cube (like an old Rubik's cube, a photo frame cube or a foam toy die).

Number of tags needed: 6
Number of reader needed: 1