One-dimensional (1D) nanostructures, such as nanowires and nanotubes, are critical building blocks that have the potential to impact many emerging and proposed areas of nanoscale science and technology. This presentation will focus on exploiting our fundamental understanding of growth and physical properties of these nanoscale materials to design and assemble rationally functional nanoscale tools and devices. First, the orthogonal assembly of semiconductor nanowires into integrated multi-terminal electronic and optoelectronic devices and the resulting properties of these structures will be described. Second, a new concept for a carbon nanotube based molecular scale computer will be discussed together with proof of concept experiments. Third, critical tools for imaging, sensing and manipulation at the single molecule scale, which are based on the unique mechanical and electromechanical properties of nanotubes, will be discussed.