Hey there, have a look at this:

http://www.youtube.com/watch?v=ggVLnb_3T4c

Shapeshop is kind of "blob-based" (Meta-balls? can't remember what it's generally called)
But I guess it could be NURBS-based without too many problems...

Anyway, just a thought, with the whole sketching approach MoI is aiming at.

could be nice to sketch out an idea, and then refine it afterwards :)