OK, I work in radio, and believe it or not, SPOT LOADS are actually DROPPING!! Thats right! You should be hearing LESS commercials lately, then in the last few years. This is in response to listener complaints of "too many commercials".
They are also trying a new "JACK" format. Inspired by the success of IPODS and 1000 song playlists set on SHUFFLE. These radio formats are supposed to play EVERYTHING and you could potentially hear a Metallica song segway right into a neil young song. Its possible! Its the "We Play EVERYTHING" format, and it will take about a year to find out if its going to work or not.
If you want to advertise, Radio is the way to go. Beats the daylights out of print media, you get a larger audience, and the rates are a LOT lower. Heck, I can get spots for as low as 5 bucks a minute during off hours. However, in the middle of a football game can get as high as 500-1000 bucks a minute, but look at your captured audience!!
Speaking of football, MOST of those commercials are forced on the radio station by the FOOTBALL TEAM! Radio PAYS for the right to broadcast the game, the football team makes money selling commercials, and the radio station makes its money by running pre and post game shows loaded with commercials. Most sports radio stations dont make money on the sport itself, but on the shows leading into and out of the event.