A few of the many places online to find answers to riddles are Game Solver, Riddles Brain Teasers and Thinks.com. Offline, Joseph Rosenblum and Joyce Behr's 1976 book, "Biggest Riddle Book in the World," is available from Barnes & Noble and other booksellers.
According to The Organic Mind, riddles are very good for the brain. Answering riddles without help improves the speed, problem solving, memory, attention and flexibility features of the brain. The Organic Mind recommends 10 minutes of brain training a day using riddles or brain teasers. The brain is compared to a muscle that must be worked to gain strength. The Organic Mind also recommends Lumosity, which offers brain training programs featuring scientifically designed games and exercises.
The Organic Mind hosts a riddle directory and offers users the opportunity to submit their own favorite riddles for the directory. Game Solver offers riddles and answers at more than 140 levels of difficulty, as well as other riddle games. Riddles also can be found in books, newspapers and magazines.
One example of a riddle is, "How do you keep a rhinoceros from charging? Take away his credit cards," from "Biggest Riddle Book in the World." A more difficult riddle is, "Apples for leather, leather for silk, silk for tobacco, all to get milk." The answer, revealed on Riddles Brain Teasers, is "bartering."