...other than walk.

About 25 miles into a ride this morning, my freehub stopped working. Seems like the pawls failed to engage as I could spin and spin the pedals and cassette without delivering power to the rear wheel. Fortunately, the 3 miles back to where I was staying was downhill. This happened without warning that the freehub was going bad. Realizing this was an impotent mechanical maneuver, all I could think to do was take the wheel off and spray some water at the top of the cassette (of course, didn't work).

Other than walking and coasting downhill, with typical tools on a ride, what can you do to fix this if this happens mid-ride?

Also, any way to prevent this in the future? Is there preventive maintenance I should be doing on the freehub? How often?

(I have had problems with freehubs before: http://www.bikeforums.net/showthread.php?t=253118)