All of the different burlap tablecloths I have looked for online seemed pretty expensive to me, especially if you are in need of large ones that don't come ready made or you need 20-30 for a bunch of tables. The problem with regular fabric is that you usually need a sewing machine, otherwise you are left with an undesirable (in my opinion) unfinished edge.
The solution: no sewing (yay!) - I found a great number of ideas on some blogs and sewing tutorials.
Burlap (BurlapFabric.com or go to JoAnn's or HomTex Burlap for Canadians)
Fusible Tape or Stitch Witchery
Ironing board and iron
Step 1: Cutting the burlap. You need to make sure that you cut it carefully so that the ends aren't too raggedy, otherwise stitching the end is going to be a nightmare in terms of having a nice straight line. If you aren't comfortable, practice your burlap cutting skills on a separate piece first.
Now onto step 2. Here you have two choices:
Option 1 - No-Sew/Semi-Sew
About.com has a tutorial for how to use fusible tape. There also a ton of other tutorials and videos. You can search "sewing hem alternative" on eHow.com and find some really good advice.
Option 2 - Hand Knotted Burlap Tablecloth
You may not want to use the sewing alternative, in which case you can just use your hands to finish the edges by making knots to get something like in the photo below. This neat idea is courtesy of Antique Chase.