Legitimacy of AFR gauges

[TomoHawk]

Measuring the coolant temperature is easily done with a temperature sensor like a thermocouple or the LM35 temperature sensor.  The  Lm35 gives a signal in millivolts proportional to the temperature in degrees C, and you can make an offset circuit for it as well, because 0C related to 0.5Volts, or display it directly using an Arduino program.

Is there a practical electronic sensor for intake manifold vacuum.  That's also important for having the engine work efficiently.