"I've used the Micro-Light and Ultra-Light switches over the years but sometimes they were too large and/or bulky for a tiny location. Then, a developer approached me at an event and gave me one of these to try. Worked perfectly for the person I was helping!" RJ :-)
Even lighter touch than the switches referenced above, just the barest touch sets it off. Only measuring 3/4" square and 1/4" tall, it squeezes in almost anywhere.