Here is my most recent build for a 4-channel, mixer sequencer. Meant to be played by 2 to 5 people. 
4 audio inputs are turned into patterns and beats by the "conductor."

http://i31.tinypic.com/15n80sg.png

Anyone have advice or corrections?
If anybody wants the full-size image, feel free to ask.
Much thanks to Pete for inspiration and aid.