The best free alternative to Notational Velocity is Google Keep. If that doesn't suit you, our users have ranked more than 100 alternatives to Notational Velocity and loads of them is free so hopefully you can find a suitable replacement. Other interesting free alternatives to Notational Velocity are Microsoft OneNote (Freemium), Simplenote (Free, Open Source), Evernote (Freemium) and CherryTree (Free, Open Source).
Top Task List is simple, elegant and responsive task organizer. You can turn a task into a start screen tile, give it custom colors, priorities, edit multiple tasks at once, shake the phone to move completed tasks out of the way, create sub-tasks, etc.
An android app for writing and storing AES-128 encrypted notes. Supports notes, checklists and even spreadsheets. It is the only app in play store offering multiple security options like password protection, pattern lock and pin lock.