Awhile ago I wrote about how one can mount remote computer filesystems using ssh. That was for Linux. You can do it with Mac OS X as well, but FUSE (File System in UserSpace) isn't installed by default, as it is in modern Linux systems.
Next is sshfs itself. There seem to be many versions, but Google's seems to work well. Download the appropriate version for your OS (the Leopard version works on Snow Leopard), rename it sshfs, make it executable, and put it in your path. From then on it works pretty much like in Linux, with minor differences. Assuming you have a directory ~/hal on your Mac, you can look at the files on your Linux machine hal with the command
sshfs rchawk@hal:/home/rcjhawk ~/hal
So a file named /home/rcjhawk/Documents/testthis.doc on hal will appear as ~/hal/Documents/testthis.doc on your Mac.
And it's simple to unmount it: