Check out the trailer to ‘Dr. Horrible’s Sing-Along Blog’. Joss Whedon, creator of Buffy the Vampire Slayer and Firefly/Serenity, has announced that his musical Web superhero series Dr. Horrible’s Sing-Along Blog will be streamed for one week, beginning July 15, 2008. Part one of the series goes up on that day, July 17 will be the debut of part two, and the third part airs on July 19. All three parts will remain available until midnight July 20, 2008. After that day, the series will be available for paid download in some format, and ultimately will end up being released direct-to-DVD with some extras as well. Whedon says that more information will be provided at the San Diego Comic Con. The series was written by Whedon during the WGA strike with his brothers Zack and Jed, and Jed’s fiance as co-writers. The story focuses on a down on his luck supervillain, played by Neil Patrick Harris, his nemesis, the heroic Captain Hammer (Nathan Fillion) and the girl at the Laundromat he’s too shy to talk to (Felicia Day). To see the trailer click on the player below.