Hmmm, this seems like a minimalist version of my tab manager, Tabli: http://www.gettabli.com

Tabli is based on a similar concept (being able to save sets of tabs with a meaningful name), but is a full-featured tab manager, allowing you to see all open tabs, switch between tabs, and revert to last saved version of a tab set.

What's the roadmap / vision for Tabbie and how does it differ from Tabli?

(To OP: If the projects seem similar enough in spirit and you'd be interested in combining forces and collaborating on Tabli, please let me know!)