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.
The Colonial Wargaming blog has a discussion and photos of various forms of tabletop hills and mountains, from the “rugged” to the “stepped” to the classic General Tremorden Rederring style profile mountains.
Here’s a nice tutorial on making insulation board hills for your wargaming table.
Hills are among the most basic sort of terrain you need for a wargames table. Here’s some nice advice on building inexpensive cardboard hills.
The Schild en Vriend site has a nice article discussing hills, mountains and cliffs on the wargames tabletop