RFOverlayScrollView
January 04, 2013 • MIT License
RFOverlayScrollView is an NSScrollView subclass that shows its NSScroller in iOS style even when a mouse is attached.
ESScrollView
May 15, 2011 • BSD License
ESScrollView by Jonathan Dann provides iTunes-like scrollbars. This solution differs from many others by not requiring images -- all drawing is in code.