Todo.txt - Track your tasks and projects in a plain text file, todo.txt. A todo.

KosmoTime - The to do list with super powers

Task Coach - Task Coach is a simple open source todo manager to keep track of personal tasks and todo lists.

Cron - Cron Calendar.

CherryTree - A hierarchical note taking application, featuring rich text and syntax highlighting, storing data in a single xml or sqlite file.

Vimcal - Vimcal is the world’s fastest calendar, beautifully designed for people who work remotely and live in their calendars.