I like computer games, it keeps my mind of things, help me relax. It is suggested that in order to keep the brain fit as we age it is important to keep it stimulated. Use it or lose it applies to the mind as well as the muscles. It is also suggested recently that it may be possible to train people to be more intelligent, increasing the brainpower they had at birth.
Therefore these fun interactive anti-aging online memory games. To make your brain sweat. There is some advertising but Firefox captured just one pop-up. My favorite: Secret Files.
Or try Five Free Fun Games When Bored, my favorite: Mario Tetris