http://bucks.blogs.nytimes.com/2011/04/19/all-about-your-unused-rewards-points/?partner=rss&emc=rss Pop quiz time. First of all, guess the value of the frequent-flier miles, hotel rewards, credit card points and other loyalty program currency that Americans earned in 2010. The answer? About $48 billion, according to a new joint study from Colloquy, a loyalty marketing research company, and Swift Exchange, a new company aiming to make it easier to blend and spend points from various programs. And that doesn’t include cash discounts that grocers and other retailers often offer.