As in years past, many Super Bowl (search) advertisers are guarding the secrecy of their 30-second spots with the zeal of a Kremlin intelligence operative. Even so, one thing seems certain: Gas-passing horses, crotch-biting animals and accidental bikini wax treatments will be nowhere in sight.

Just ask advertising executive Jeff Goodby, whose firm did the now-infamous Budweiser spot in last year's game in which a draft horse spoiled a romantic evening for a young couple riding in a hansom cab. "This year, I think most advertisers are going to be incredibly well-behaved," he said.

That ad and others in last year's game caused concerns in some quarters that the advertisers had gone too far in using ribald humor to grab the attention of the young, male audiences that marketers try so desperately hard to reach. That perception was only made worse by Janet Jackson's breast-baring episode in the halftime show.

Goodby is still in the game this year, but he sees which way the wind is blowing. "Everybody knows where the line is, and I don't think it will be crossed," he said. "It's implicit in the process that you're not going to get your client in trouble this year."

For this year's broadcast, which airs Feb. 6 on News Corp.'s (NWS) Fox television network, Goodby's San Francisco-based firm of Goodby, Silverstein & Partners (search) is producing ads for two clients, the Subway restaurant chain, owned by Doctor's Associates Inc (search) of Milford, Conn., and Emerald of California (search), the snack nut division of Diamond of California, a grower cooperative based in Stockton, Calif.

The Emerald spot is a far cry from the horse ad, and depicts a father and young daughter sitting on the couch in their living room.

Dad tries to deflect a request from his child to share the Emerald nuts by saying that if he does, unicorns will disappear forever. A moment later, a unicorn strides into the living room and chides the nut-hoarding parent: "Ah, that's not true, Jack." Santa Claus and the Easter Bunny, also the subject of previous threats, chime in as well before Dad hands over the nuts.

Several other advertisers, however, are keeping their spots under lock and key, hoping to create a sense of anticipation and mystery. That tactic worked wonders a generation ago for Apple Computer Inc. (AAPL), when it introduced the Macintosh computer in 1984 with an iconic ad featuring a runner hurling a sledge hammer against a giant image of Big Brother.

Anheuser-Busch Cos., (BUD) which once again will be a top Super Bowl advertiser, isn't talking yet about its plans. The nation's largest brewer purchased 10 of the 30-second commercial spots for its Budweiser and other brands. It also will have what's known as category exclusivity, shutting out Adolph Coors Co., Miller Brewing Co. and other beer makers.

Keeping Super Bowl ads secret until just before game day has become a tradition, partly because the competition on game day is just as fierce among the creative minds of the advertising industry, who want to showcase their best work, as it is among the players on the gridiron.

Volvo, a first-time advertiser in the Super Bowl this year, has toiled to put together a spot to launch a campaign for its new V-8 sports utility vehicle. But John Maloney, who handles advertising and marketing for Volvo Cars of North America, a unit of Ford Motor Co. (F), is keeping the actual ad tightly under wraps.

"Right now, the (ad) is secret, so stay tuned," Maloney said. "First, part of being on the Super Bowl is the anticipation of what you're going to see. Two, we have a particularly unique execution that, quite frankly, we don't want anyone else to know what it is."

Visa spokesman Michael Rolnick was equally tightlipped about their spot, which will extoll the security features of Visa's check card. Will the ad be funny? "It is, and that's all I can tell you right now," Rolnick said.

Fox is asking $2.4 million for each half-minute ad this year, up slightly from the $2.3 million rate last year when Viacom Inc.'s CBS network broadcast the game won by the New England Patriots over the Carolina Panthers. The ads have been selling fast this year, and Fox says it is about 95 percent sold out.

Entrepreneur Bob Parsons has already been fielding questions about whether he's doing the right thing by ponying up for 30 seconds of fame. His company, Go Daddy Group Inc. of Scottsdale, Ariz., is a leading vendor of Internet names and will be making its Super Bowl debut this year as well.

With an expected $200 million in revenues in 2005, Parsons says his company is far more established than the upstart dot-coms which merrily spent their IPO money on Super Bowl ads in 1999, only to go down the drain later. Sure, the ad for the www.GoDaddy.com web site is expensive, Parson allows, but "if the thing is a complete whiff, we're still fine," he says.

That still doesn't mean he's going to let the cat out of the bag. "The ad will be different, something beyond what anyone has seen before, and beyond that I'm sworn to secrecy," Parsons said.