Not sure if this has been proposed before, but haven't seen it myself.

Desktop shortcut widget

Basically this would let you place normal looking shortcuts in the desktop, but when you select it, it opens a small group of shortcuts defined by you. It may be a circle around the original place or a rectangle to some direction. Then you could just select the shortcut you want to launch an application.

And perhaps if you click to any other place on the desktop without launching anything, it would close the shortcut group.

This could be like the circle dock: http://circledock.wikidot.com/. But just around the widget shortcut that you place on the desktop where you want.

I think this would be a nice way to save some desktop space while still enabling you to launch your favorite applications fast.