These guys (http://blueshiftpdx.com http://blueshiftpdx.com) have a speaker system that runs entirely on super caps. It charges in 5 minutes and plays for 6 ho

These guys (http://blueshiftpdx.com http://blueshiftpdx.com) have a speaker system that runs entirely on super caps. It charges in 5 minutes and plays for 6 hours. Downside I guess is its a bit expensive.