The graphite sheet of a carbon nanotube is not simply "rolled up" as in a normal graphite fiber. Instead, the edges are covalently bonded together, forming a seamless tube as opposed to the "rolled carpet" formation of a normal graphite fiber. This eliminates virtually all dangling bonds at the edges of the sheet, making the carbon nanotube less reactive.
Also, the chirality of the nanotube, or amount of twist in the structure, controls the electronic properties of the nanotube, making it either a semiconductor or a metal.
Some theoretical calculations by IBM show that the electrical properties of a metallic carbon nanotube can be altered by physically twisting the nanotube. It seems that twisting a nanotube changes its chirality, creating a bandgap proportional to the amount of twist.
This property could lead to interesting transducers like a nanoscale torsion balance where the bandgap of the wire (and therefore its resistance) varies with an applied gravitational or electromagnetic field.