I would like to be able to set up a folder on my Mac, where I could dump files and have them be automatically sent to the default printer. This way I would be able to print files at home when I'm not physically at home, using something like Dropbox. It wouldn't have to be real-time; i.e., a scheduled job that checks the folder every so often would be acceptable. What's the easiest approach? Automator? Applescript? Cron job?
Use automator and create a folder action. When you drop a file on the folder, the action is taken.
As an intro, create a folder and control click or right click on it. You should have a menu that says "Folder Actions Setup..." or "Enable Folder Actions..." depending on your version of OS X. Then choose an action like "convert to JPG"
These actions are written in Applescript or Automator framework. Inside that framework is anything you want, such as Perl, Bash, Applescript, or Automator actions.