Depending on where you camp, you don't even need poles with a tarp - just string it up between two trees (with a ridgeline, or with cords off each center grommet.) This gives you a pup-tent style rig. You can tie off two corners to two different trees (or to a line strung between two trees, and pitch a lean-to. Finally, you can tie off one end to a tree, and peg the other to the ground, yielding a wedge.