I just learned about Workflowy. It is a super duper easy todo/note taking/organizing/cheat sheet/mind map/brain map/whatever tool.
Disclaimer: I earn 250 items/month if you follow this link and register to be a member.
It is free to use for 500 items/month and you get 250 items/month for each person using your link to register. Pro version is $4.99/month or $49/year, which is not that bad for this fantastic tool.
Give it a try!