Shelfit - Worry less about juggling multiple windows or deciding where you want to store things. With Shelfit you can quickly open up a shelf, drag files in, and then when you're ready just drag them back out.
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.
Droplr - Droplr is a tiny application that aims at helping people share things easier.
Dropover - Mac app for easier drag & drop
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.
Dropshelf - Dropshelf is a place to put things. Drag anything to the edge of the screen, and a shelf slides out.