Ground tarp...

[-FiveFiveSix-]

While I like, and use, garbage bags, another option is grab a coupon and hit up JoAnns for a yard of coated oxford nylon and cut it down if it's too long. A little heavier and a lot stronger than silnylon. I would not stand on my rainwear. YMMV. ;-)

Howdy neighbore (Rochester NY) I may look into this aswell, my good freind's wife works at JoAnns, I may be able to score a good deal...

[FLRider]

I use an old GI poncho. Indestructable (or nearly so), and you can get them in whatever drab color or camo pattern you want. It's heavy, but that's the price you pay for a quad-use item (rain gear, pack cover, improv Grizz beak, and ground cloth).

As long as you're not setting up on a field of shattered obsidian (and, if you are, I want pictures, durnit!), it should hold up just fine to whatever you do to it.