I've been using Evernote a lot lately to map out the design for a tactical RPG and so far I'm really liking it. I can paste pretty much anything into it, and it syncs with every device I own (which means any time I get an idea, I can add it... no matter where I am.)
It's also good for grocery lists.
Saw this on Reddit recently...
Pretty neat stuff. May have to incorporate this into my next project.