A new class of fast radiation imaging detectors is described. Radiation-induced photoelectrons, or secondary electrons, emitted from a thin convertor are multiplied in gas. The surface conversion, emission and multiplication of these eV electrons is characterized by a subnanosecond response and a high resolution parallax-free localization. The low-pressure operation considerably reduces the sensitivity to direct gas ionization and permits the operation at very high radiation flux, with a reduced occupancy. The properties of UV, X-ray and thermal neutron imaging detectors based on this principle are reviewed. Fast RICH and TRD devices are discussed as well as other potential applications.