Dropbox Automator is a powerful web app that connects to your Dropbox account and monitors the folders of your choice, performing automated actions you define whenever new files are detected. This can be anything from converting a document to PDF, resizing images and uploading them to Facebook, plus a whole lot more.
The setup process is pretty simple. You'll need to authorise Dropbox Automator to access your files to get started, and when doing so it will show up as Wappwolf -- the service that powers it. Once you've got that out of the way, you can select a folder you want to use for automation.
Unfortunately you cannot create a new folder from within Dropbox Automator, so if you want to add a new one you should do that on your local machine before you log in. Once you select the folder you want, you can start assigning actions from the provided list.
They're all pretty self-explanatory, but the labels on some of the action options are not as straightforward as they could be. If you read them carefully they'll make sense, but currently they appear to be labelled by their method names. Once you're past that little bit of confusion and you've selected all your actions, just save your choices and you're all set. Now any relevant files placed in the Dropbox folder you chose will be subject to the automation you set up.
Note: Processing takes a minute and the results will show up in a folder called "results". A folder called "processed" will appear first, containing the files that were just processed. Those will be the unaltered copies. Wait for the "results" folder to appear to see the actual results.
This is a very useful tool that can do a lot with the stuff you keep in your Dropbox without any work on your part. It's still a little rough around the edges, but definitely worth a look.