A VimOutliner-based master todo list
TKDO is a CLI and PyGTK program designed to work with VimOutliner files. It takes all your todo.otl outlines, merges them into a single flat list, auto-sorts them, filters them, and adds support for things like contexts and recurring events. It also has one somewhat unusual feature -- a snooze button. It's easy to mark tasks as "don't bug me about this for a while".
The entire system is based on plain text files, with a GUI to make certain tasks easier and faster. Due to its plain text nature, it's easy to extend or customize the system with short scripts.
If you have a lot of todo lists scattered across many directories or even multiple computers, TKDO is useful as a "master list" to access all your lists at once. I like to keep a todo list in each project directory, and TKDO makes it easier for me to track all my projects from a single place. Otherwise, there would simply be too many lists to check.