We present the study of spin and charge transport in nanostructures in the presence of spin-orbit (SO) interaction. Single band tight binding Hamiltonians for Elliot-Yafet and Rashba SO interaction are derived. Using these tight binding Hamiltonians and spin resolved Landauer-Büttiker formula, spin and charge transport is studied. Specifically numerical results are presented for a new method to perform magnetic scanning tunneling microscopy with non-magnetic tip but in the presence of Elliot-Yafet SO interaction. The spin relaxation phenomena in two-dimensional electron gas in the presence of Rashba SO interaction are studied and contrary to naive expectation, it is shown that disorder helps to reduce spin relaxation.