This is the one I use. My group is usually 10 peeps or less, so it's a good size. 12 X 15. Well made, light weight, made in the USA. Marty at Wilderness Logics does good work and he'll get the tarp to you fast.
WILD RIVER GUIDE TATP
I have also used the Noah's tarp. It's a pretty good tarp for the price, but I didn't care for the way it pitches. Never good get it taut because of it's shape.
"We are all visitors to this time, this place. We are just passing through. Our purpose here is to observe, to learn, to grow, to love....and then we return home."
Australian Aboriginal Proverb