For those of you who listen to scanner radios, there's a useful search utility for finding aviation-related and other frequencies. It's called the Radio Frequency (TAFL) Search, courtesy of Industry Canada.
If you know the latitude and longitude of your city, you should be able to do a Geographical Area search between 118 MHz and 134 MHz to get a comprehensive listing of air frequencies in your area. Other searches can be done by company name -- particularly useful for finding other airline frequencies and the limo services who sometimes divulge who they're picking up and where they're taking them.
You might also find emergency service frequencies, as well as the transit frequencies which can often be more interesting than anything on TV.