Sales of Procter & Gamble's (P&G) Pepto-Bismol had been flat or declining for several years when in 2010, P&G marketers noticed that social media chatter about the pink indigestion reliever was occurring on Saturday and Sunday mornings -- presumably after users had overindulged the night before. So P&G decided to try to lure potential customers before their eating and drinking binges by touting the product on Facebook with the upbeat slogan "Celebrate Life." The result was an 11% market-share gain in the 12 months through fall 2011. Although P&G won't disclose how much of the $9.3 billion it spent last year on advertising went to social media, the company says it's increasing the share of its marketing budget allocated to sites including Facebook, Twitter, and Google's YouTube, as well as sites prominent in overseas markets. More recently, P&G has built social media campaigns around issues important to consumers it wants to reach.