Bike lawyer Josh Zisson, of Bike Safe Boston, had these cards printed up so that bikers would have immediate legal recourse if they got in an accident. The cards sport a clear graphical representation of Massachusetts' bike laws, and space to record the details of the accident, the driver's plate number and insurance information, and witnesses' contact details.
If you're in Massachusetts, they're a great last-minute gift for a bike enthusiast (though we recommend not letting the recipient open this one in front of an anxious mother). They're available at bike shops all around the Boston area, or you can contact Zisson. If you're not in Massachusetts, maybe this will inspire you to make your own showcasing your state's laws, or get original designer Timothy Jacques to do it for you.
UPDATE: You can spare yourself the trouble, Zisson is making versions for other states! Send him an email if you want some — josh at bikesafeboston.
The Bicyclist’s Accident Report Card, Selectism.