Octojack is a multi-device controller (for steppers, DC motors, solenoids, servos, LEDs, GPIO, etc) for easy experimental prototyping (e.g. animal behavioral paradigms). It's centered around a Teensy microcontroller, and can perform many of the functions of far more expensive NI DAQ boards.
We developed an inexpensive ($200 USD), yet precise electrical stimulator for neuroscience. Stimjim features two isolated outputs capable of both current and voltage control with microamp/millivolt resolution and microsecond temporal resolution. This device is now being distributed by labmaker and open-ephys.