i think the spray painting accross the kite is a good idea...it doesnt have to be an ugly "X" accross it, but somthin a little more stylish. I come from a sailing background, and i found a stolen sail on the side of the road (worth about $3k), anyway i contacted a few forums and within 6 hours i found out who's sail it was...all they had to do was discribe the sail number and colour, and it was done.
so why dont we all get a number system happening, and stensil-spray them on-to our kites, kinda like a VIN number on a car, but much more visable. maybe the last few didgets of ya car licence or d.o.b or somthing..
just a thought, id hate to get ma new kite stolen, i'd cry