Dropzone - If you want your file uploads to work even without JavaScript, you can include an element with the class fallback that dropzone will remove if the browser is supported.
DisplayFusion - DisplayFusion will make your multi-monitor life much easier.
Dropover - Mac app for easier drag & drop
WindowGrid - Quickly and easily layout windows on a dynamic grid using just the mouse.
Unclutter - Unclutter is an app that is designed to help Mac users bring order to their desktop. Among other features, this powerful piece of software provides quick access to a user's notepad and clipboard.
Mizage Divvy - Divvy is an entirely new way of managing your workspace.