clipt is CLI (Command Line Interface) Pomodoro Timer. Although the name mentions command line, but it is flexible to be equipped with and support a GUI interface. It's a multi-user program written in C for Unix that allows each user of the system have their own Pomodoro timer.
Project has moved to: https://github.com/craigk5n/gtimer
GTimer is a GTK application for timing how you spend your time among various projects and tasks with support for generating plain text and HTML reports.