Cut off the cord. Take a pair of snips and cut the cord as close to the base of the microwave as possible. Even if the microwave is broken, make sure it's unplugged when you do this. Place the cord inside the microwave.
Check out your local laws. Because of their electronic components, microwaves are usually considered hazardous household waste in most areas. Check with your city of county government for specifics. Find the listings in the blue pages of the phone book or see the Resources section.
Go national. If you are having no luck finding somewhere to dispose of your microwave at the local level, find a recycling location through the U.S. Environmental Protection Agency. This agency is listed in the blue pages of the phone book, or see Resources.
Get creative. Instead of getting rid of the microwave, use it for another purpose. Glorious art can be made from any debris. You can open up the microwave and use the small innards in your next collage or mosaic. Leave the microwave intact and cover it with a small tablecloth to make an end table. Paint it and take off the door to store books. Leave the door on for an instant, airtight storage chamber.