The microwave is usually frowned upon by ambitious chefs. It provides a convenient way to quickly heat ready made meals or the leftovers from the day before, but it is usually not regarded as a serious kitchen utensil (as is testified by one of the answers below).
However, it seems to me that the unique way in which a microwave delivers heat should open up possibilities for food preparation that simply did not exist before the introduction of this device.
Not being an experienced "microwave chef" myself (in fact I never had access to one until very recently) I ask myself:
Aren't there any crazy avantgardistic or molecular cuisine type ways of preparing food that exploit the specifics of a microwave oven in an unconventional way?