Acoustic travel-time tomography of the atmosphere has been successfully demonstrated in several field studies during the past decade. This paper discusses potential applications where tomography can provide valuable information on the atmosphere, focusing on four particularly promising ones: (1) imaging the four-dimensional velocity and temperature fields of near-ground flow structures including testing the homogeneity of micro-meteorological measurement sites; (2) using the spatial averaging characteristic of tomography to validate large-eddy simulation closure models; (3) providing data on very stable boundary layers, where current numerical simulations do not work well; and (4) passive localization of sound sources in the atmosphere by accounting for atmospheric refraction and advection. With regard to this fourth application, a new technique is discussed for localization of sound sources with simultaneous reconstruction of the vertical wind and temperature profiles.