Find a nearby electronics recycling service and make sure they are reputable. There has been issue with e-waste (electronic waste) being exported to developing countries that can not properly handle it.
A good company in the United States is All Green Electronics Recycling. They offer free service and have over 100 drop-off locations and do free pick-ups all across the country. Check out www.allgreenrecycling.com or call (800)780-0347