We have developed a new and versatile source of cold (ΔE ~ 0.018 eV), low-energy (E ~ 0 - 9 eV), magnetized positrons and electrons. Particles are extracted from thermalized, room-temperature, single species plasmas confined in a Penning trap. Typically, the trap contains from 10 7 to 10 9 particles, which can be released either in the form of a quasi steady-state beam or as a pulsed beam. Of the order of 100 pulses of 10 5 positrons, each 10 μs in duration, have been achieved. Size, duration and frequency of pulses within a pulse train are easily variable over a wide range. Cold quasi steady-state electron beams with a diameter of ~3 mm have also been achieved. Limited only by the total charge contained in the trap, electron currents of 0.1 μA for several milliseconds have been generated routinely. This source represents a combination of attractive features not previously available using any single technique.