Know How to Hold 'Em Building an online community can pull customers onto your website--and keep them there.

Joey Shamah didn't set out to create a social network for cosmetics enthusiasts. But after introducing a beauty blog and other community features on his cosmetics website (eyeslipsface.com) in June 2007, e-commerce sales leapt 50 percent, and the length of customer visits tripled.

Shamah, 27, has a vested interest in beauty. His $20 million company, Eyes, Lips, Face Cosmetics (e.l.f. for short), sells oodles of eyeliners, lipsticks, glosses and other makeup under its brand. About half those sales are generated through the website, and many of the items go for about $1 each.

At that price point, margins are slim and e.l.f. can't afford the celebrity-endorsement marketing embraced by cosmetics giants, says Shamah, who founded his New York City business four years ago. So he looks to everyday makeup wearers to create brand buzz. For example, you can earn gift certificates for making web referrals that turn into sales transactions.