Here's a quick tip for the type of terrain you almost never see: roads. Although they provide an in-game bonus, I can't think of the last time I saw a table with roads on it.
The tools and materials are simple and cheap. All you need are a single asphalt shingle, tin snips, card stock, your hobby knife and some spray paint. Single shingles are usually sold at most home improvement stores to do spot repairs. The best part is that they only cost about a dollar and each shingle will give you about 6 linear feet of roads.
First cut the three flaps off, at the width of the pre-cut notches. This yields about three 5"x12" pieces. Then you can either cut the other side of the shingle to the same width or (especially if you are using several shingles) you can make wider 6" roads.
If you want to make some curves, just leave one of the three notched pieces and cut a curved section. The easiest way I've found is to freehand cut a curve and then use a section of already cut road to trace the other curve to cut.
Once you've got your roads cut, just cut stripes and numbers out of the card stock and use them as a stencil for some quick spray paint road markings. Marking the curves is a little trickier.
So there you go: cheap and easy roads. Just don't tell your favorite local tournament organizer how cheap and easy they are to make or he might ask you to make roads for every table. Will they all get done before WAR Games Con? Sign up and come on down to find out!