Dr. Horrible's Sing-Along Blog is the brainchild of Joss Whedon, who has enlisted his friends Neil Patrick Harris, Nathan Fillon, and Felicia Day to create a musical in which Dr. Horrible (Harris) blogs about his daily routine, reading fan letters, and of his attempts to join the Evil League of Evil. Captain Hammer (Fillon) is his nemesis and Felicia Day (a Buffy alum) is his love interest that he never talks to. Part 1 is up on the web for free for the first week before they sell it on iTunes, and Part 2 comes out on the 17th, and Part 3 comes out on the 19th. Each segment is approximately 15 minutes long, and there are talks of a film version, a Broadway musical, and a sequel. You can also watch it on Hulu, ad-free!