I like how older threads keep living here on OB.
I used to only use old green canvas tarpaulins when camping...heavy, pretty well impervious to rain, and long-lived if you treated them right. Even hitch-hiked with one down to the Smokies when I was 15 and rigged it up to sleep underneath. Nowadays with cool solar-tech fabrics and rip-stop nylons, etc, not sure if technically they're "tarps," but I use them now for shade and protection from the rain, and let the vinyl tarps do their work as footprints under tents and such.
I think this one is actually a sun-fly, but used it to protect the hammock on a short camping trip to Hocking Hills in Ohio. That's a Grand Manan tent with another tarp under it. Great tent. The whole set-up withstood one of the heaviest late night thunderstorms I've ever camped through. Wild and windy. Both tent and sunfly stayed standing while most of the tents around us collapsed. We stayed dry as a bone.