Great concept, but the UI needs work. Rated 3 out of 5 stars
This addon has potential to be a great tool, and is something I would use regularly. Several problems, though...
1. I'm accustomed to accessing options for my extensions via the addons window--but TabTimer's options button is greyed out and inaccessible. Forcing users to go through the tools menu is unwieldy and inconvenient (in my case, my menu bar is hidden to save screen real estate.)
2. A toolbar button would be nice. A status bar button would be even better.
3. An edit option for existing TabTimers is necessary.
In short, if it were just easier to access with a more user-friendly interface, I could see myself using this addon. As-is, it's just too much trouble to go through. That said, I'm eager to see how the future versions turn out.