There are a ton of papers written about this field. I've been bushwhacking through them. Google Scholar is your friend in this. There's a good overview of procedural methods here: http://www.st.ewi.tudelft.nl/~iosup/pcg-g-survey11tomccap_re...

Thus far, I've been focusing more on procedural content generation/procedural -anything- related to gaming/storytelling. Togelius has a lot of good stuff.