BoundsBox extension was used for drawing rectangles on map a few posts ago.
The new version of BoundsBox (1.0) has option to insert images inside (visible or invisible) rectangles. The image is attached in a draggable pane of map. So it pans with map. It scales when map is zoomed. It is attached below markers, so it doesn't eat marker clicks. The behavior is equal to GGroundOverlay of v2 api.
A few more options and methods were introduced with the new version. They mainly serve image handling like opacity and z-index. Events 'imageloaded' and 'imageloaderror' are also provided.
See an example with a table of options and methods.
The most latest version provides also an alternative constructor KmBox(). Instead of LatLngBounds it takes LatLng and kmX, kmY dimensions as its parameters. As a side product we got LatLng.destinationLatLng(bearing, distance) method. That calculates LatLng 'that many kilometers from this LatLng to that compass bearing'.