We describe a compact, economic and versatile diode laser system based on commercial laser diodes, optically stabilized by means of feedback from a diffraction grating. We offer detailed information which should enable the reader to copy our set-up which uses only easily machined mechanical parts. Our system offers single-mode operation with a linewidth of a few 100 kHz, continuous scans over 25 GHz, high chirp rates (up to 9 GHz/ms) and FM-modulation up to the GHz range. We discuss radio-frequency phase-locking of two independent lasers systems, allowing well controlled fast frequency switching which overcomes the limitations imposed by acousto-optic modulators.