Brain Age, Train Your Brain in Minutes a Day is discussed on Wikipedia

Brain Arena is the best online brain-training available. Thousands of players from all around the world compete against each other in tests of mental ability to demonstrate that theirs is the most exceptional mind.

Brain boosting puzzles and games for children

Computer games have long been derided by critics as mindless, brain-rotting fun. But a new wave of games is turning the cliché on its head. Nintendo has sold nearly five million copies of its three Nintendo DS brain training games since the series launched in Japan a year ago. The first title in the series, Dr Kawashima's Brain Training: How Old Is Your Brain?, sees players follow a daily regime of brain-enhancing exercises and is due to be released in the UK in June. Dr Kawashima's Brain Training comprises a variety of mini-games designed to give brains a workout. Activities include solving simple maths problems, counting people going in and out of a house, drawing pictures on the Nintendo DS touchscreen, and reading classic literature aloud into the device's microphone.