bup is now more popular than all my other projects combined
...at least if you measure it by counting the number of watchers on github.
It is also featured in the top 100 or so interesting github repositories, although there's no particular indication of what they mean by "interesting."
(Previously: bup: it backs things up. It's matured quite a bit since then, though, and is now usable for backing up real work that you care about.)