Fans of Joss Whedon, goofy superheroes and oddly engaging musical numbers can now rejoice - Act One of Dr. Horrible's Sing-Along Blog is now available at the online-only musical's website.

From the creator of of Buffy the Vampire Slayer and Firefly, the show tells the tale of 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).

Act One went live on Tuesday, July 15, 2008. Act Two will become available on July 17, and Act Three will air on July 19. All three parts will remain available to watch for free 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.

To watch Act One CLICK HERE