From the same guy that brought you the array sketching script, comes a new feature: Surface sketching.
This clever script allows the user to paint the basic outline of a mesh with a grease pencil, and the script fills in the gaps. As the video demonstrates, this new technique for modeling can be an incredibly fast way to model complex shapes.
The only downside I can spot is that because the grease pencil doesn't show perspective very well, the user may get confused/disorientated whilst painting.
Potential uses for this script include: terrain creation, retopology, clothing for characters and modeling difficult shapes. It will be interesting to see where this script goes.