We have a poll running on this site asking what is your favorite summer Olympic Games sport? The clear leaders at the moment are swimming, gymnastics, and track & field. This also matches the results of the most viewed sports on the Olympics website in 2004. To most Olympic watchers, the popularity of these sports is not surprising, but it should be if you consider that the undisputed most popular sport in the world (world football/soccer) is also one of the sports on the Olympic program, and other very popular sports that are on the program are basketball and tennis.
Outside of the Olympic period, you rarely see swimming, gymnastics, and track & field televised, and there are no stadiums full of spectators at these sports every week. The reality is that they are not that interesting to watch – except at the time of the Olympics it seems. It is football (whatever code), basketball, baseball, cricket and many other sports that are more popular with the fans week in and week out. At Olympic time, unfortunately, it is not just the sports fans that are watching, so the most entertaining sports are not necessarily the most watched and getting the most attention.