Badia DragNCopy

Duplicate items by simply dragging and holding the Option, Control or Command keys

With DragNCopy, you can duplicate items by simply dragging and holding the Option, Control or Command keys. You can now drag and duplicate single, multiple or grouped items interactively, without using a dialog. DragNCopy also remembers the offsets of the last drag and copy operation, so you can generate additional copies of the last operation simply by pressing Command-D.