http://www.armaholic.com/page.php?id=12898
It adds all manner of assets back into the editor menus. Need to add a couple of houses and can't get the TownGen to place them properly? No problem.
Don't use the Full version, as that requires everyone who joins the mission to have the addon. With the lighter version you still get:
[AS] Residential - Residential houses, apartments and the like.
[AS] Commercial - Commercial buildings
[AS] Industrial - Industrial buildings, equipment, pipes, tanks etc.
[AS] Interioir - All the little things you find inside buildings.
[AS] Military - Military buildings, fortifications, targets etc.
[AS] Misc - Lot's of misc. things. Imagine that.
[AS] Mosque Set - Contains all the pieces of the large mosque. (OA only)