App Box for Dropbox (was QuickSaver for Dropbox) lets you access Dropbox super fast. Browse, download and upload files without even opening your browser or finder. Just click the QuickSaver for Dropbox icon in your menu bar and sign it with your Dropbox account, its that simple. You can also switch to the stand alone desktop mode for full window experience (requires Pro). To upload files you need to be in window mode.
Note: Now requires OS X 10.10 or later.