Legio Wargames has a tutorial on basing your figures with wood filler, sand and other bits.
basing
Using Children’s Board Books For Bases
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.
Making Desert Bases
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.