A variety of novel applications for the investigation of disordered surfaces by beams of thermal energy atoms are discussed and illustrated by numerous examples. A straightforward semiclassical approach is introduced to yield a remarkably detailed insight into the lateral distributions of diffuse scatterers such as adsorbates, vacancies and atomic steps. The recent discovery that the long range Van der Waals force is the cause of the unusually large cross-sections for diffuse He-scattering on individual defects and impurities led the authors to propose a new methods of surface analysis. They...