I found this very useful in merging changes for Octopress, granted I ended up having to wipe the entire project out anyways.

git remote add upstream https://github.com/imathis/octopress.git

This way I’m able to fetch anything that happens to the master of octopress by simply running

git fetch upstream

If I want to go ahead and merge:

git merge upstream/master

I can’t tell if there’s a difference between using https:// or git://, so I’m sticking to what github uses as an example.