I use it on the body work - well, just the front really, it gets rid of flies wicked! Hose the bike down, a generous spray of muc off, leave 5 mins, then wash with the regular car shampoo stuff.
Ride magazine rated some stuff called Hippo as the best, but none of my local shops sell it, and can't be arsed doing mail order for cleaning stuff.
WD40 is excellent for getting crap off wheels, like grease etc. But caution says spray on a cloth then apply, as it coulod go anywhere!