Los Angeles Airport's Noise Monitor software

The City of Los Angeles owns the airports. The entity that controls airports in Los Angeles is the Los Angeles World Airway. You can track overhead flights in near real-time at:

http://www4.passur.com/bur.html

800-441-0409 - 24 hour noise complaint

a new browser will open and on that page you will see a lot (but not necessarily all) the aircraft aloft in and around Los Angeles. See the screenshot I've attached. Passur no longer gives LAX as a base, but does give the Burbank airport. You will have to use the compass feature to move down to LAX. (updated 11-Jan-2009). The website uses Adobe Flash stuff, so it revs the CPU a bit.

It is wise to remember that under a certain altitude, no aircraft are visible to LAX' radar, and therefore won't show on the map.