It's important to tie in technology with an objective. If not, you risk the chance of using technology just to use it. It's important that the technology enhance and reinforce the lesson.
Students should be accountable for stations/centers for several reasons. First of all, it shows that they are responsible for the station, the technology and the work being done. Secondly, it teaches them to value things. whether it's the technology being used or the quality of the work being done.
The 2 sites I liked the most were Learning Games for Kids and Thinkfinity. These were the 2 sites that really had the most to offer in terms of music. Although stations are a little harder to do in music it is possible. We have limited technology in our classrooms but that is starting to change. We are also limited by time. Since we do not see the students daily, we really must make sure the station reinforces the unit we are doing so we can maximize the time spent with the students. Some possible stations are listening stations, reading stations (composer books), rhythm station, music math and music theory stations. To hold students accountable, equipment should be checked out. As students move to stations they should report any problems, any misbehavior or misuse of the technology, which should lead to that student sitting out or being disciplined.
Some of the apps we currently use are Nota, inTone, Tap DoReMi plus many songs have interactive apps. For a station the student or students use the ipods or ipads to do an activity for "x" amount of time. Nota for example breaks it into lessons and a quiz. Results from the quiz can be emailed to the teacher.