The survival course I attended last month in Central Alberta used a military cargo chute, suspended from (inside) a large tripod, as a classroom. It wasn't completely waterproof - we had some ferocious thunderstorms that week and we ended up standing around underneath the chute wearing our raingear - but whereas we were pretty comfortable with the raingear inside the shelter, we'd have been soaked without it. And it took some pretty ferocious rain to get through it.
It provided pretty good shade when the sun came out, as well. The school made no attempt to use the parachute as a tipi; the edges were about 5 feet off the ground so it was more of an open-air shelter.
I always had the impression that using a parachute for survival purposes was not so much because of the quality of the cloth/material, but because a lost airman might (once) have been reasonably expected to be equipped with one.
Building such a shelter in your back yard from an army surplus parachute would certainly make you popular with the neighbourhood kids, I expect <img src="/images/graemlins/laugh.gif" alt="" /> But as far as chopping it up to use for other projects, I have no experience with that.
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"The mind is not a vessel to be filled but a fire to be kindled."
-Plutarch