Games for the Brain has over thirty games, you can start at the first game and progress through them in sequence or you can pick and choose the games you want to play.
As you finish each game you are given a score which is added to your cumulative "IQ" score. Most of the games are timed and if you wait too long to answer you will lose points. This helps keep you involved and keeps your brain working.
The site offers a very nice variety of challenges and does of good job of making you think and forcing you to use some of those spare brain cells that usually just sit there doing nothing.