Curve tools similar to 3d coat. The ability to use curves with different profiles that you can edit and wrap around a mesh or just freestyle (chain, rope, wire, hair, zipper etc...). Not limited to just the surface of the current mesh. (I know you can kind of do this with the current curves and vector displace, but you are limited to the current object surface).
Now that we have dynamic tessellation, this would be an excellent addition.