Idea Tree (Android) app for FREE
Idea Tree's unique interface helps you arrange your ideas into a hierarchy of notes. Use the level slider to quickly drill down into details or jump back up to your headings. Organize and outline everything in your busy life with ease, set a password to keep your thoughts to yourself, or share your plans by exporting or e-mailing in text, HTML, or CSV format. Idea Tree automatically keeps old versions, so you can restore previous notes if you change your mind, or just compare your current ideas with old ones.