Inspirations

Saw a post the other day asking what we thought the best settings were to play in, now I can't find it.  But it made me wonder about the other side, when you are world building, what are you best sources and inspirations?

I use the 1e DMG alot, if it's a medieval setting I grab Chivalry & Sorcery for their kingdom creation rules.  Warhammer has some great guidelines for distribution of towns and villages.  I'm reading Adventurer, Conqueror, King's campaign rules right now and I love them.  So what have I overlooked?