Microsoft found a potent way to make friends on Facebook: offer users of hyper-popular social game FarmVille virtual currency. The in-game offer on Tuesday resulted in Microsoft’s Bing page gaining 425,000 fans in a single day, more than tripling the 117,000 fans it had. The program, created by digital agency Deep Focus and brand engagement network Social Vibe, shows the potency of the exploding world of social gaming, fueled by currency that lets players buy virtual items. Zynga’s FarmVille is a runaway smash on Facebook, boasting over 82 million players who tend crops and raise livestock on virtual farms.

via Bing’s Virtual Bling Buys Facebook Fans.