In this preview for tonight’s 30 Rock season finale, Alec Baldwin’s Jack Donaghy basically blackmails Mary J. Blige, Elvis Costello, and an unrecognizable Clay Aiken into performing at a charity concert for his newly discovered, kidney-deficient father. A commercial for this episode–which will also feature Sheryl Crow and Rob Thomas, because they tend to show up on these sorts of things–promised “an ending that will end up on the Internet,” which I thought was a given since every single episode of 30 Rock has been on Hulu, like, the next morning, but maybe that was a subtle hint that NBC is really serious about getting into the whole music-blog thing? [NBC]