The point of this Rsync script is to sync the files that have changed so that we don't make more work then is needed. This will compare the files from the source to the target then once if finds the files that need to be copied it will compress the files and then copy them to the destination server. I set up the script to run on a regular basis.
This will run every midnight at 12:03AM, archive mode + compress, use a password file, syncing source folder with destination folder with username.
0 3 * * * rsync -avz --password-file=/password_file /path/to/folder/ USER@server.com::path/to/folder/
Look for the directions on how to setup a rsync server. Also note that this should work fine on Mac OS X but I have not fully tested it on the OS.