Ask anyone what's hot in advertising, and you'll hear about viral video, social networking, etc. Even as the industry embraces the Internet, however, there's been an unexpected renaissance in the original old media: outdoor advertising. Spending in this segment of the industry approached $7 billion in 2006 and is on track to grow by 8 percent this year, while network TV, radio, and newspaper advertising is expected to remain flat.

Because outdoor ads can be cheap to produce (we found several campaigns that cost less than $5,000) and can be tailored to local constituencies, they would seem to play to the strengths of entrepreneurs. "A small marketer has a bigger opportunity to make a big splash now than ever before," says Chuck Porter, of the Miami ad agency Crispin Porter + Bogusky. The savviest campaigns will often get picked up on design and advertising blogs like the Cool Hunter.

Many of the best outdoor ads lift ideas from art installations and force customers to do a double take. "If you've done something clever," says Kevin Keller, a Dartmouth marketing professor, "then consumers will have a chuckle and feel good about your brand." Here are nine outdoor ads that have earned buzz.

  1. Pounding The Pavement
    In March, New York City manhole covers were reimagined as steaming cups of Folgers coffee. The New York Post called the ads "pretty realistic--except for the unjava-like aroma." A spokesperson for Procter & Gamble (NYSE:PG), which makes Folgers, says P&G may devise outdoor stunts for some of its other well-known brands.

  2. Rainy Day Fun
    Turning its customers into walking billboards, Gloss, a Vancouver hair salon, offered clients transparent umbrellas bearing the slogan "Hair You Want to Show Off." Owner Ceanne Chow says the promo was far more effective than any traditional ad she has ever run. And the campaign was dreamed up for free by a local agency that wanted to enter a campaign in an advertising contest.

  3. Getting a Grip
    "It's not really a campaign, it's just a bag," says David Mously, who designed this campaign for Stop 'n Grow, a nail-biting deterrent sold in Europe. Mously's design turns the bag's handle into a gaping mouth. Drugstores in Germany distributed 10,000 of the bags in late 2005. The campaign spread to several other countries last year.

  4. Gone to the Web
    Vacant shop windows need no longer be depressing. EBay (NASDAQ:EBAY) recently posted "Moved to eBay" stickers in empty storefronts all over Belgium--a campaign that "shows graphically" that small retailers can find a new lease on life online, Dartmouth's Keller says.

  5. Wheels of Fortune
    "We wanted something different, I guess," says Cliff Wilkins of the upside down eight-ton semi he placed at mile 211 of Oklahoma's Interstate 35 to promote his truck repair shop. The truck is held erect by poured concrete buried 14 feet deep. Installing the truck cost about $9,000, and though Wilkins says he can't quantify its impact on sales, he gets a half dozen inquiries about the ad every week.

  6. Soul of The New Machine?
    "Life is too short for the wrong job," reads this ad for a German job hunting website, which depicts imaginary workers toiling inside vending machines, ATMs, and photo booths. The cleverness here is in the unexpectedness of the venue and the fact that the joke is both subtle and over the top. "Finding new spaces is the only option in a world filled with advertising junk," says designer Matthias Spaetgens, of the agency Jung von Matt.

  7. Special Delivery
    This ad for Papa John's (NASDAQ:PZZA) sticks to a door at peephole-level. Though it won the Golden Lion award at the 2006 Cannes advertising festival, the pizza franchise halted what a spokesperson describes as a "very limited" rollout among its stores in Peru after receiving complaints.

  8. Builder's Envy
    Using giant-size posters to create a clever optical illusion, a toy distributor transformed five buildings in Santiago, Chile, making them look as if they'd been constructed entirely from Legos. The total cost was $5,000.

  9. The Jaws of Love
    Executive Search Dating, which bills itself as a matchmaker for overworked professionals, placed jaw traps baited with faux Rolex watches and BMW key chains in Vancouver's financial district. "Leave the hunting to us," a nearby sign read. The three-month, $5,000 campaign boosted sales by 15 percent, founder Paddi Rice says.