Not sure if anyone has seen Surface Sketch for Blender but it looks like a really cool extension. 
http://wiki.blender.org/index.php/Extensions:2.6/Py/Scripts/Mesh/Surface_Sketch
Time Lapse Video
Tutorial Video
Looks handy! Although the video is three years ago. Is this addon already in blender? I can’t seem to find it.
Yes it’s bundled with Blender 2.67 and above… took me awhile to figure that out. It’s now called BSurfaces. So if you enable the BSurfaces addon, that’s it.
http://blenderartists.org/forum/showthread.php?183863-Surface-Sketching-script-v0-8-Beta/page10
Dustin, TY for that link - I was unable to find it - just like Bridin. And like Bridin thought maybe it had died with Blender 2.5.
There is another video here:
The modeling of the violin is amazing to watch (last half of the video).- and it seems to be about 2 years old.
Don’t bother following the “www.bsurfaces.info” link on the Blender Artists page it leads to a website on teeth whitening ! 
On the topic of retopo, blender cookie has an addon that can help too - video here:
cheers, gryff
Bummer, I was looking forward to trying it out this weekend. 
Thanks for the other link though Gryff! I’ll check it out.
