iPhone and text docs, and when I want to think a bit more about the idea, Google Sites. The latter has a wiki-like structure with lots of useful structures (e.g

iPhone and text docs, and when I want to think a bit more about the idea, Google Sites. The latter has a wiki-like structure with lots of useful structures (e.g. headings, LHS hierarchy, some widgets, lists) and I can share it with others very easily. Keeps version history.