I have a workmate who only uses a Mac. Being unfamiliar with Mac text editors, I'm wondering if anyone can recommend one that will allow SFTP access using ssh keys (not just passwords).
Cyberduck has integration support for many editors. http://cyberduck.ch/
With it you can browse (edit) FTP, SFTP, WebDAV, Cloud Files and Amazon S3.
They would probably use the included OpenSSH libraries. So you would just need to add the public/private keys in ~/.ssh/
I personally use rsync to synchronize the working set and the remote directory. Write a small batch file, double click and it synchronizes within a few milliseconds. If you don't need concurrent editing then this will probably be the more sane solution as you don't need to worry about slow filesystem abstraction layers. MacFuse is great in theory, but I have had it lock up finder a bit too often for my liking.
Cyberduck and TextMate integrate very well - Cyberduck lets you use SFTP, and TextMate is one of the best Mac editors around.