Necromundicon is awesome, but you might not see why at first. Beyond a nice collection of Terrain How-To Pages, there's also a lot of great inspiration to be found on the Gothic scenery (don't miss the effects page) and Industrial scenery pages.

Tehnolog is a Russian gaming company (cue Yakov: "In Russia, wargames play you!" ) that makes games that are warhammer like I think), but they also make really cheap terrain sets for wargames. Nice bits. They're available at the The War Store for pretty cheap (small boxes US$10).