Dropbox Automator is exactly what it sounds like, a tool to automate certain tasks on Dropbox. It similar in some way to ifttt.com in some respects, but it's restricted to Dropbox.The tool can watch certain folders and act on files that are placed there. It can convert images into certain formats, convert documents to PDF files, upload documents to Google Docs and so on.
There is quite a long list of actions, useful if the service is going to appeal to a lot of people. Any file can be emailed to certain email addresses, compressed, encrypted and so on.
More specialized actions are available for certain file types like images or documents. The tool has just been opened up to registrations and it got 10,000 users in 72 hours. The fact that Dropbox has tens of millions of users certainly helped.