The Super Bowl isn't just the biggest football game of the year, it's also the biggest event for Madison Avenue. This year the ads are costlier, but also a potentially better investment.
So why are advertisers flocking to a single event, where a mere 30 seconds of ad time costs as much as $4 million, plus often another million or so to produce a commercial?
Because it's still the best way to reach a massive audience, who treat the ads with just as much respect as they treat the game itself. And now brands can get more bang for their buck by extending their ads for weeks before and after. (Read More: Why Wait? Super Bowl Ads Are Already Online.)
Marketers also have more low-cost options than ever, and more tools to target and measure web ads.
After last year's game drew a record 111 million viewers and sparked unprecedented Twitter buzz, this year CBS brought in an average of $3.8 million per 30 second spot. That's up from an average of $3.5 million last year, and up 60 percent from a decade ago. (Read More: For Super Bowl Ads, It's Viral or Go Home.)
Of course, CBS is a big winner. It will bring in an estimated $350 million from ads during the game, plus pre-and post-game coverage, according to Kantar media's Chief Research Officer Jon Swallen.
The broadcaster will benefit from selling the national ad time, and it also owns the major affiliates, including San Francisco and Baltimore, who sell the local ad spots.
The fact that the same advertisers spend millions—if not tens of millions of dollars—year after year, indicates that the investment must be paying off.
(Read More: 12 Most Unusual Super Bowl Bets.)
Anheuser Busch InBev has been the biggest advertisers in recent history by a long shot, spending about $250 million over the past five years, according to Kantar Media. This year Bud is back, buying four and a half minutes of ad time, including the first commercial of the game.
PepsiCo is the second largest advertiser over the past five years, spending $183 million, according to Kantar, and this year it's back with another big investment. The beverage giant will unveil two new spots for its flagship soda and Pepsi Max, and that's on top of sponsoring the half time show. And for the seventh consecutive time Pepsi's Frito-lay Doritos brand is soliciting user-made commercials in its "Crash the Super Bowl" contest.
Doritos solicitation of customer participation has been ahead of the curve; now more than a half dozen brands have an interactive element in their campaigns. Both PepsiCo and Budweiser are bringing consumers into the ad-production process.
Budweiser, which just launched a Twitter feed, is asking people to tweet in names for its baby Clydesdale. Pepsi's "Crash The Super Bowl," which asks people to vote on which user-created ad they want to see on game day. Plus, Pepsi's half time ads will use hundreds of fan pictures. (Read More: Twitter Ups Its Game in Super Bowl Ads.)
Pizza Hut is asking fans to submit a video of themselves. And a number of brands are giving fans a voice in which ad will run: the goal is to get consumers engaging with an ad long before it runs, and ideally, to share it with their friends, which is the most valuable type of free advertising.
Coke is debuting a campaign in which fans can vote on the ad's outcome—one of three groups of thirsty travelers is rushing through the desert to reach the soda. Audi is letting viewers which of three options will make the game.
(Read More: Friday Night Lights' Peter Berg on Directing Super Bowl Ad.)
And as more marketers release ads early, some are already cashing in, long before game day. Mercedes Benz' ads featuring model Kate Upton is the most popular ad on YouTube so far, with 5.5 million views. Toyota's game day teaser, "I Wish" has the second-most hits, more than three million so far. And yet another automaker is in the number three spot, "Audi," with its "Prom teaser ad," which has about two million views
—By CNBC's Julia Boorstin; Follow her on Twitter: @JBoorstin