For instance, yesterday I took a nap at midday, because I'm on spring break and I'll do what I please, thank you very much.
When I was dreaming, I dreamt that I was in this place where I'd hung out with my friends, like a hockey rink, and everything was so different but so familiar. I found these old notebooks of mine, and opened them up, and there were these bizarre pictures of men with swords and with these wierd, gun-arm things. In the background were enormous white, patchwork-steel towers that projected a translucent blue sheet into the sky. The combination of them made them look like transparent blue plates of glass riveted together, and I knew that the world was ancient, that the technology that goes into protecting the world is being destroyed, and that the blue plates were what were keeping people alive, between the devastated atmosphere and the meteor showers, and acid rain and all of that beauty. The natives were half-barbaric savages, the last remnants of a planet-spanning empire that permeated all of their stories and subconcious. It was a world of destruction and remnants of ruined dreams.
When I got up, I wrote it down immediately.
This stands in stark contrast to when I look at my blog and say to myself, "Dude, you haven't updated in like a month, go write something about that stuff you were thinking about," and so I lazily slap together some words and call it a day because if you don't stay in the habit of writing you'll never write anything.
The other cool thing I thought of in a dream is basically a plugin for magic, where in order to get any magic the spellcaster has to sacrifice something or obey a taboo for each spell, like if they want to cast fireballs they must have a taboo to always carry an open flame, or to always eat raw meat. The cool thing is that it starts with low-level spells so even if the player is smart and gives himself minor taboos, by the time he wants to learn Grobar's Deliberate Frostfire Beam he has to decide that he's plucking out his own eyeball or scarring his face with hideous tattoos or something. And that's if he hasn't already done that...