Long time ago I have tried to open FreeMind mind map on an Android tablet and failed due to very limited possibilities.
Today I tried it again and finally found an ideal application SimpleMind that can import/export mind maps using FreeMind format.
C Programming mind map
Debian Crypto Incident mind map
A quick map of what, where and how to use FreeMind mind map
Every mind map mentioned here can be downloaded from the Mind map gallery.