* take two musicians, pick a scale, and trade quarter notes: see if you can match the note the other person just played a quarter note ago, pick up on ascending/descending patterns or whatever. I have had a little experience with the standard jazz practice of trading four measures at a time, but doing it at the resolution of single notes is something I'd like to try.
* take a bunch of people, have them agree on a rough tonal center, and then have each one write down a melody spanning a fixed duration (I'd imagine like two or four measures) All people then try to put something together that uses all the melodic bits once in some order. Kind of like serialism on a larger scale, only it might sound good :P
