Excessive sweating of hands, feet, and axillae (armpits) is a distressing symptom to those affected. Often the treatment is not completely satisfactory or too expensive.
As an introduction to the topic, there was a good article in the NY Times: Rx for Patients who Sweat Too Much. If you want more information, you can visit the International Hyperhidrosis Society. (Keep in mind that these organizations often receive support from pharmaceutical or device manufacturers)