For drying modest quantities of herbs, a microwave oven can work quite well. It may be just the ticket in humid conditions that make air-drying almost impossible, and for herbs such as basil that tend to lose both color and flavor with traditional drying methods. The key is to monitor the process closely and to adjust microwaving time and power level according to the manufacturer's instructions for your oven.
On its website (geappliances.com), GE Appliances warns against using paper products containing recycled material in a microwave, since these may include bits of metal that can arc or ignite.
Because of their relatively low moisture content, herbs are about the only thing that can be dried successfully in a microwave oven. Other foods, such as tomatoes or berries, contain too much moisture and wind up cooked rather than dried.