I've got some ideas rattling around for use with a NoSQL database and started looking in to them again. My hurdle was always wrapping my head around the MapReduce functions and understanding the basic concept for filtering data. 2 sites which did help (and I figured worth sharing) are:
- MapReduce – The Fanfiction, told via a Star Trek story.
- MapReduce, a visual explanation. (thanks to @neurotic for that one)