Here's a beauty tip for your home. We are really busy and everyone eats at different times in our house, so we use our microwave oven a lot. When it's time to clean and refresh your nuker try this natural and cost effective cleansing technique.
Pour 2 cups of water in a microwave safe container and mix in a tablespoon or two of straight citrus juice, either fresh or bottled. Lemon, lime, grapefruit - it's your choice. Microwave the water uncovered until it reaches boiling and continue to boil for a minute or two allowing the steam to build up in the unit. Leave the oven closed and let the cleansing steam work to remove odors and food particles. After 5-10 minutes open the oven door (there will be a lot of steam so be careful) and remove the water/citrus juice mix and dump it down your food disposal to help refresh it too. With a damp towel wipe down the inside of your microwave and let it stand open for a bit to air out.
If your microwave just needs a quick refresher wet an absorbent cleaning rag or towel (I use a bar towel) with water mixed with lemon juice and place in the unit. Nuke for about 2 minutes and let set for another 2 minutes. Wearing gloves to protect your hands - the towel is going to be pretty hot - wipe down the inside of the microwave and throw the towel in the wash. Don't you just love a simple solution!