Occasionally I've run into the need to either Zip or Unzip a file once it's up on my FTP server. I was pretty sure this was possible but I'd never bothered to figure it out until recently. You might not ever find yourself having a need for this, but if you deal with the occasional client who doesn't really understand compression, you might find yourself pulling off a few 30GB+ folders from time to time. Basically it's fairly straightforward (if you're using Transmit, but let's be honest - what else would you even be considering?). Step 1 was to enable SSH access on your web server/FTP. Over at Bluehost, all this took was 2 minutes with a quick message to their online support chat, they enable it on their end for your account. Next, you need to be logged in to *SFTP* as opposed to basic FTP.
Step 3 is to zip/unzip to your hearts content. With your file selected, go to the File menu and at the bottom you should see *'Send SSH Command'*. The lovely developers at Panic have included the ability to send the zip commands automatically for the programmatically challenged. Just click the gear icon and pick your poison, no typing required. Then just let it work its magic, and in a matter of minutes or seconds depending on what you're doing you'll be all set.
So to recap:
1. Enable SSH 2. Use Transmit, login via SFTP 3. File > Send SSH Command > Zip/Unzip
Hope that helps anyone looking for how to do this.