Though it's been just days since the Carrie Underwood-lead 'Sound of Music Live!" premiered on NBC, and the network is already working on another installment. What exactly they'll be performing next, though, is anyone's guess.

Having garnered more than 18 million viewers, NBC's live production of "Sound of Music" served as one of the network's most successful endeavors to date, with call-ins flooding in over the weekend requesting further live performances. NBC Entertainment Chairman Robert Greenblatt, understandably, was psyched. As he told the New York Times:

"All weekend, people have been calling us and e-mailing us. Please do one of our shows.' We're excited to try it again ... there's enough to do a handful of these over the next years ... I think we could do this again -- and again and again."

Production for "Sound of Music Live!" took 18 months, so expect another musical in that much time from now.