I finally found the holy grail.
That's right. An LED bulb that works in an over-the-range microwave.
Though I love LED bulbs for the energy savings, in this application, it's more than saving a few bucks in electricity. They just burn out all the time. It seems like literally every single month I have to change a bulb in the microwave. Apart from the fact that Home Depot gouges you for 4 bucks a pop for these replacement T8 bulbs for microwaves, it's annoying to keep changing it. I have longed for an LED replacement for longevity.
Here it is, in all it's raw glory. I ordered this straight from China, since in the US, apparently there is a conspiracy to ensure a steady stream of T8 bulb sales, and there is no such product available.
While this particular bit of nascent imported technology doesn't seem to have a name, your crucial search criteria on Ebay are E17 LED (the base is E17). It is easy enough to tell by the pictures on ebay if the bulb is going to fit in a microwave. The ones I got were about $3.50 apiece shipped... less than a conventional 30-day-life-expectancy bulb.
What about dimming?It doesn't dim. On the other hand, it doesn't freak out either. Most over-the-range microwaves have two "on" settings, full power, and half power. When set to half power, it's mostly off (a few of the LEDs still light, but it's not really usable). But nothing bad happens either, I've left it this way for long periods of time with no ill effects. I've personally never cared about the "dim" setting anyway.
About 5 watts total (2 bulbs x 2.6 watts), versus 50-80 watts for two incandescent bulbs. So basically it's a nightlight. Just leave it on all the time if you feel like it, it'll cost you about 30 cents a year.
How's the light quality?
It's not as great as a high-quality residential LED warm white bulb but who cares? It's for over the stove. It's bright enough and not too harsh.