`git rebase -i` is your friend. Check it out! (No pun intended.)
Also, if you push a generic WIP commit, like Will suggested, you can just `git reset` to the commit before that on your other machine and proceed to commit different pieces of it after.
Bonus tip: you can `git push -f` to a remote as much as you want, but just don't do it on branches of e.g. a pull request that others may have checked out already. And you can't really lose anything, if it was on your machine before, `git reflog` is your friend for that case.
