I had an idea once while playing Day of Defeat, but because of my zero skill in model building never took it anywhere
How about making a standard building, but "distress" it by making the surface texture covered with bullet holes, blast marks, broken areas and so on. Then "clad" the whole thing in a patchwork of ultra thin panes (additional objects) that can be easily destroyed by gunfire. The theory would be that if a player sprayed the building with bulets then the "clean" texture would fall away, revealing the pockmarked and scorched wall underneath.
If you really wanted to go bananas you could make multiple layers to the onion, with the inner layers having more damage ability and greater visible damage. By making the varous "panes" impassable (until destroyed) you could even make an object whose geometry changes as you shoot it up.
Example - Brick wall defined as a smooth textured pane ("x" damage), over a pock marked textured pane ("10x" damage), over a low rubble textured pane ("100x" damage). Do enough damage to the thing and you can either climb over it or walk through it.
Am I mad or would this require way too many objects and or too much work to create ? :-\
Roni