W Mass as a Calibration of the Jet Energy Scale at ATLAS
  Top-antitop pairs will be copiously produced at the LHC, at a rate of roughly one per second at a luminosity of10^{33} cm^{-2} s^{-1}. These events have low background and produce large numbers of jets via the hadronic decay of the W's which may be used to calibrate the jet energy scale and resolution with experimental data and simulations. 
Daniel Goldin