Kevin’s Miniatures and Hobby Table Blog has a photo tutorial on making small hills out of cork.
I was inspired by these World War I bits of scenery. I especially like the “rough ground” pieces.
The Maiwand Day blog has a very nice photo essay on making a rocky hill from wood chips. It’s immediately on my project list.
DJK’s Fantasy World has a tip for using leftover casting plaster to make rocky terrain.
The Mini Stories blog has a nice photo tutorial on making snow bases.