If you have ever researched bug-out-bags, wilderness survival, and survival articles in general, you will find tarps listed as a survival must. There is a reason for this of course, because they are versatile. Emergency shelters usually come to mind, but they have other uses as well, many other uses.
1.) Make a Hammock
Making a hammock out of a tarp will require some work, and the tarp material must be heavy enough to support your weight. There is any number of reasons to get up off the ground for sleeping, and a hammock is an ideal solution.
First you would want to make a knot out of the fabric at both ends. This can be difficult to do, and it is not the only way to make a hammock, but it is the fastest, and requires less cordage. Make the knot and then tie cordage below the knot to hold in place as you put weight on the hammock. Tie the cordage off at both ends to stout trees. Then, once constructed you can then secure a tarp over the hammock to block the sun, rain, and dew.
Instead of tying a knot in either end you can wrap cordage around the twisted ends of the tarp, and then secure off to a suitable tree. The grommets in most tarps would not be strong enough to thread the cordage through and then tie off, so you would have to twist the material together to make it strong enough to hold.
2.) Make a Litter
Tarps can be used to carry injured people if you have the personnel to lift the four corners with a person on the tarp. Otherwise you would have to drag/pull the tarp with the load on it. This would be extremely difficult to do alone.
You can drag lighter items such as game kills or supplies using a tarp or you can make a travois, or drag sled and then make a harness from cordage so you can pull/drag it. Stretch the tarp between the poles to put your supplies on.
3.) Mattress/Ground Insulation
Fill up one side of the tarp with dried grasses, pine boughs or any material that is suitable for sleeping on and can act as ground insulation. Once you have enough material roll the tarp up to secure the bedding material.
4.) Use as a Tow Strap
If you twist the tarp tight and tie off or put a knot in each end, it can be used as an emergency tow strap to pull your vehicle from a ditch or snow bank. This requires another vehicle of course to do the pulling. You would need a heavy tarp and it can be difficult to twist and then knot both ends. This is an emergency procedure only however. Once used in this manner you would never get the knots out, they would be pulled to tight.
5. Rain Catchment
There are various ways to collect rain water. One is to dig a shallow depression in the ground and line with a tarp, and let the water collect and then scoop out. You can also suspend a tarp between poles and let the water weight create a depression in the tarp. This will require that you collect the water quickly to prevent the tarp and poles from collapsing however.
Lay the tarp out and collect morning dew or lay it over some low growing foliage. Let the dew collect in the depressions in the material.
There are literally 101 uses for a tarp around the house, and there are some survival uses that could literally save your life, so think about other uses in a wilderness situation and for around the home as well, uses that might save your life.