A very important tool in the toolbox of any collaborating developer is a merge conflict resolution tool. OS X has the fantastic FileMerge, there are various graphical tools for linux like kdiff3, but I have yet to hear of one for the terminal. There's vimdiff, but it is really not up to the task of merge conflict resolution (doesn't handle 3-way diffs). There's probably something in emacs, just because there's always something for emacs. Emacs users please enlighten me, I'm not above using emacs for merge-conflict resolution. Might even be the gateway drug.
It doesn't seem overly hard (at least, no harder than writing kdiff3 or FileMerge) to make an ncurses tool that will take a 3-way merge and let you efficiently choose A, B, or edit for each diff section. Can it really be that nobody has done it yet?