ryanpyle and I used the cardo system during our early rides together, and it's fantastic being able to communicate about hazards, asshats and other dangers, and also just to shoot the breeze. the cardo is bluetooth, so limited to line of sight and about 500m, but when it's working it's great. voice activated. battery lasts 24 hours or more. great fidelity. I think Ryan and Colin are using the Cardo system during their MKRide.

my chinese buddies mostly use citizens band, so everyone is in the same channel together. this requires some discipline. CB has great range, and they swear by it.

cheers