Are there any tools bundled with OS X which can assist me with automatically synchronising a folder with an FTP site?
I have CyberDuck but what I am after is automation.
You can map a remote SFTP folder to your local computer using SSHFS with FUSE for OS X (based on the old MacFUSE, which does not work on 10.6+). After that, all usual tools such as rsync are available to you:
mkdir /tmp/my-server sshfs user@remote-host:/my-dir /tmp/my-server -oauto_cache,volname="My Server" rsync -aP /tmp/my-server $HOME/my-local-copy
...or to eject the disk from Finder's sidebar: first go into Finder's preferences to make connected servers show on the desktop, and then when connected drag the disk into the sidebar. OS X will remember you once dragged it in there, and show it whenever you connect again.
You could use the built-in ftp client and an expect script and then have that called from an Automator script run at an interval (scheduled from iCal).
I've never done this myself, but all the pieces are there.
Folder Actions are what you're looking for, along with Automator scripts.
Check it out:
I use sitecopy, an FTP sync application. It's commandline. It's included in fink, the OSX lib that contains a lot of linux tools ported to osx
Depending on your level of comfort with the tools, you could certainly write a bash script that would do what you're after. That would require a bit of understanding of the underlying Unix toolset, but it could definitely do what you want.
I suspect that you could use AppleScript or Automator to do what you're after as well.