Instead of a physical microswitch, a proximity/touch sensor is often useful. This can be used to detect opening/closing of a lid or door, or as control as a switch, or as objects or parts of a mechanism move past, or a bunch of other things. Really handy!

I've built some of these based on 15mm-range IR LEDs and phototransistors, followed by an opamp as level comparator to generate a digital output. Having one of these to plug in seems useful; it would probably sense "sideways" rather than "up" from the PCB to have the best application form factor.

The LED/phototransistor combo I've used is the Vishay TCRT1000 ( http://www.digikey.com/product-detail/en/TCRT1000/751-1031-ND/1681165 ) but there are others, too. I used a MCP601 opamp, but again, there are plenty to choose from :-)

There is also the microwave solution... But yes having a proximity sensor would be nice.