The biggest thing tying my team to GitHub right now is that we use Graphite to manage stacked diffs, and as far as I can tell, Graphite doesn't support anything but GitHub. What other tools are people using for stacked-diff workflows (especially code review)?

Gerrit is the other option I'm aware of but it seems like it might require significant work to administer.

I use git town. Fits my brain a lot better.