Your best source for inspiration for RPG's?
In the past I would say television series, because of their episodic nature, but that's not really the case these days. Right now it is tumblr, or rather a couple of photoblogs of fantasy or sci-fi artwork. I see a particularly evocative illustration and start building the backstory. Take this example, of a dead giant king whose remains have become the foundation of some ruin...
There's loads of them out there in the Wild West of the Internet, aka Tumblr, but here's a good example of a fantasy blog: Meanwhile Back in the Dungeon (NSFW)
For science fiction, a good example is Sci-Fi Spaceships
And just for fun, here's one composed entirely of spaceships from Star Trek, some canon, some not: Star Trek Ships