Joss Whedon's online music Dr. Horrible's Sing-Along Blog is now live and viewable for free here and downloadable (for not-free) via iTunes. Starring Neil Patrick Harris as a would-be supervillain nursing an unrequited crush on a woman at the local laundromat (Felicia Day) as he attempts to join a league of supervillainy, it's a three-act, 40-minute musical. The first act is up now, to be followed by two more installments in the next few days.