The new Comments area allows users to leave comments on files. This is really useful when used in combination with the Groups plugins to create a better project/file management feature.
Generate a Google Shortlink for the full file URL. This is a great way to create a temporary file name if you need to email a link to a client or associate. Just sign up with the Google API and put your API key in the settings panel.
The Download Logging System lets you view who has downloaded your files. The system keeps track of the user and date; it also tells you how many times a user has downloaded that file. All this information is accessible in the new tab system included in the free version.