When I cook something in the microwave, I generally put it in for some time between 30 seconds and 3 minutes. This usage pattern is borne out by the wear on the buttons.
I wondered if this would follow Benford's law, but it doesn't seem to. Here are the buttons arranged in order of usage, based on the amount of wear:
There's no particular reason why it should, as the amount of time I want to heat my food isn't so much related to the actual heating requirements of the food as to the amount of times I feel like getting up and stirring it. Plus a bunch of other reasons. :) Sadly I think the wear patterns are too noisy to work out if the arrangement follows a Zeta distribution.
Wear on buttons can have more serious side effects: Bruce Schneier recently posted about security-code keypads which leak information by showing a pattern of wear on the correct keys.