That list is partially right. Lately the intramurals that are offered have been based on a cadet survey taken before each semester. Here's the sports that I can remember off the top of my head from the last year:
Rugby
Flag Football
Cross Country
Ultimate Frisbee
Boxing (This is separate from the mandatory freshman boxing class)
Basketball
*Mountain biking and Soccer were definitely NOT offered*
I was a Limited On Season club athlete for the second semester, so I'm sure I'm missing a few sports that were offered.. You can still be part of an athletic club and compete with them in conjunction with competing through your squadron's intramural teams.
Also, intramurals have been a pretty big controversy among the cadets. I often heard of people who were fed up with the amount of time they took out of their day or the quality of the games which were being played. I played rugby during my first semester and there were multiple teams who really didn't care to be there and gave practically no effort. The intramural system is constantly being reworked, the past spring semester there were only four days of intamurals before the the single elimination final rounds (of which there are very few).
Finally, intramural teams are picked by the squadron athletic officers and usually run on a seniority system. Meaning that the firsties get to pick. . . first and 4 digs. . . last.
Good luck and take care.
**edit: I forgot to mention that if you are not a NCAA Intercollegiate athlete or a LOS (limited on season) club athlete then intramurals are MANDATORY FUN!