You can see in the Flick Gallery of Jeffrey Knudsen (from War Artisan) a terrific method to build a wargaming table, by using foam rubber floor tiles, a ground cloth and wads of polyester batting fixed with straigth pins. This allows to change the shape and location of the hills each time the table is built.
The effect is amazing but take into account that Jeffrey uses 10mm figures. Don't miss the other Jeffrey's Flick Galleries, with a lot of useful ideas and great AAR's of land and naval wargames. The below pictures are taken from Zweibrucken, a fall 1813 game.
Incidentally the link was found through Andrea Sfiligoi and Sergio Laliscia (the 'father' of Song of Drums and Shakos) in the Song of Blades an Heroes yahoo group.