Nanotubes are much stronger than metal wires of equal diameter, because the atoms in them are held by stronger chemical bonds than those in metals.
Nanotubes can also conduct electricity, as semiconductors.
I don't know what your definition of valuable is, so I can't say whether I think nanotubes will be what you would consider valuable. Lots and lots of information on nanotubes can be found at Nobel Prizewinner Richard Smalley's home page . All rights reserved.