Mind Maps: Scrum, Extreme Programming, Lean
Mind maps are cool. They provide a very good overview of quite complex structures and things. You may quickly scan the mind map and find interesting relations. Also it helps to create / maintain good picture of the process/structure in your head.
Agile development processes are good candidates for mind maps.
Scrum
This mind map represents Scrum checklist (PDF). Looks neat and focuses on right things like Definition of Done, correct roles definition,etc. In short it is a mind map of best practices in Scrum.
More formal mind map (PDF) of Scrum process. Plenty of details and good nodes separation. And finally a small and funny Scrum mind map.
Extreme Programming
Two very similar mind maps of Extreme Programming, but with different details.