At 32, Max Levchin may feel like the granddaddy of Web 2.0—"I felt too old for the Internet the first time around," he jokes—but four of the applications his company has created for Facebook have consistently ranked in the top 10. Levchin has been around the block: He sold the consumer e-commerce site PayPal to eBay for $1.5 billion back in 2002. His current company, Slide, makes fun widgets, such as sparkly photo shows that let you pep up your Web site and MySpace page. He says his current strategy is to "build things that we generally thought were missing from Facebook." SuperPoke is an extension of the existing Facebook poke application, the digital version of being, well, poked by someone. Thanks to Slide, you can now tickle, drunk-dial, or throw a sheep at your Facebook friends. Users continually write in suggesting new ideas. "I don't know what they all mean, but we do try to keep them from getting too weird," he says. Levchin runs ads on his applications, but his thinking doesn't stop there. "Our Top Friends app lets you buy drinks for your friends," he explains. "So I think, What brand can be sponsoring one of our drinks?" He expects to make a million dollars by the end of the year on ad revenue alone. "Any big brands that want to simply drive traffic to their own Web sites are going to miss the chance to leverage the viral tools Facebook offers," he says.