Plain-text todo list:

1. To create a project, type a line ending with a colon.

2. To create a task, type a line starting with a dash followed by a space.

3. Everything else is a note.

4. To create a tag, type the @ symbol followed by a name.

5. Tab to indent and create outline structure.

TaskPaper started as few days TextEdit hack in 2006. It's no longer a "tiny" project in terms lines of code. But the original simple idea–plain text todos with 5 formatting rules–remains the core of what TaskPaper is.

I'm very proud of that!