Here’s an interesting idea about using an old children’s board book as a base for making terrain. I think there’s lots of other uses for this readily available source of thick cardboard.
Big Lee’s Miniature Adventure has an article comparing various methods for making desert bases for 6mm figures. The techniques, of course, can be applied to any scale.
The Pin at War Blog has a tutorial on making some nice “highland” bases for your figures. I love the look.