I was involved in Blood Bikes for a while. A volunteer organisation delivering blood/organs/xrays between hospitals for "out of hours" service, to reduce the hospitals' costs of hiring couriers.
Motorcycle medics make a lot of sense in congested streets. I remember reading about how two were amongst the first on the scene to the London tube bombings.
I like my bike because I can overtake 4x4s down farm tracks with a week's worth of shopping on the back.