A couple of different intercoms, some power supplies, a battery charger for an old photo flash, a distributed control system for my garage doors, an audio/video routing switcher, a very small, very basic time-domain reflectometer (TDR), a 1-channel color organ (just one light, not three).
DC motor, UK101 computer (from a kit), valve VHF tuner, valve and transistor audio amps, power supplies, battery chargers, central-heating controller, mic-to-MIDI converter, motor speed controller, voltage regulator, light dimmer, bedside light, video amp, aerial rotator, test gear, .....