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Sweating for a cause can be incredibly motivating—just ask Katherine Jeter, the 72-year-old who pedaled her bike from California to Florida last spring to raise more than $200,000 for nursing scholarships. But if fund-raising for a charity ride or run isn't your style, consider the Plus 3 Network. You sign up (it's free), log your exercise, and every mile on the treadmill or lap in the pool is translated into points. (If you verify your activity with a fitness tracking device, like a Garmin or an iPhone, you score double.) The site's corporate sponsors then convert those points into dollars and donate them to your favorite nonprofit. So far over 16,000 participants have stretched, jogged, and danced their way to more than $450,000 for great causes and groups, including local food banks, Greenpeace, and more. (plus3network.com)    
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