A month or so ago, my beloved dishwasher died . . . or at least its $500+ control panel did. It has now been re-purposed as an extra large drying rack.
Since all of our dishes are now washed by hand, we have the lovely task of keeping kitchen sponges clean and stink free.
Previously, prior to my dishwasher dying, I would throw one on the dishwasher with each cycle. Rotating, so one was always fresh.
Now that I no longer have that luxury, at the end of every wash session I throw one in the microwave for a minute and thirty seconds. Making sure that it is thoroughly saturated and slightly soapy. If it is too dry, it will burn . . . alas, I know this from experience.
My mom turned me on to this technique when I was in college. Circa 1997/1998, when the only way we had to clean our dishes wash the teeny tiny sink in our dorm room. The first time my roommates and I tried this, the sponge was not wet enough, it was winter and our 6th floor dorm room (on the side of a mountain) wreaked of "burn sponge" (so did the rest of the floor .. . . oops). We had the windows open for a few days, only closing them at night.
Another plus to this is, once you've nuked the sponge and let it cool for a minute or two, you can also use it to scrub the inside of the microwave. The steam will have softened any particles or over flow. . . .