Pillbox is a great new site from the National Library of Medicine that can help you identify unknown pills based on color, shape, size and markings. Identification is made easier with high resolution images.
When you’ve identified the pill you can then read all about it and see the official FDA drug information label.
If you are trying to identify a pill because of a possible poisoning emergency call the National Poison Help Hotline instead: 1-800-222-1222
Correction to this post: Poison centers have the same number nationwide, but a call to 1-800-222-1222 will route a caller to his or her local poison center.