Ever since Dr. Horrible's Sing-Along Blog first appeared on the web, the web-based series about a low-rent supervillain has been a smash hit. And with fans clamoring for more, Zack Whedon told MTV about what fans can expect to see from Dr. Horrible, his arch-foe Captain Hammer and the rest of the memorable cast.

First up, the soundtrack for the web-series will be downloadble on iTunes beginning September 2, 2008. And the second web-comic is already being written by Zack Whedon. "The soundtrack is rapidly approaching," Whedon said. "And all those cut-offs, where the songs would just end, they will be on there as they are on the show. They're just in a much higher quality, and no sound effects. I sing along to everything and it'll be weeks before I can stop. It's driven me mad. Luckily, I can still hold down a job."

As for the next web comic? It's going to focus on Dr. Horrible's "evil moisture buddy", Moist. "I'm interested in exploring how Moist became Moist," Whedon said. "It'll be Moist: Humidity Rising. He is so far from making it into the Evil League of Evil, because he really isn't that bad at all." Instead, Moist is in the Henchman's Union, because he accumulated enough hours "assisting evil people, and inconveniencing people. It doesn't take much," Whedon said.

Other possibilities for future web-comics include Fake Thomas Jefferson, and even possibly the Captain Hammer/Dr. Horrible groupies.

In the meantime, plans are still proceeding for fan-submissions to join the Evil League of Evil. The ten best three-minute video applications will appear on the DVD. "When people are supposed to be submitting, it'll be abundantly clear how," Whedon promised. "Everyone will know." Even before that, you can try to contact Bad Horse directly at [email protected], though you will get the following response:

Please stand by. P.S. Please forgive the absence of song. The Bad Horse Chorus currently is recovering from a Horrible hang-over.

Dr. Horrible's Sing-Along Blog was a three-part web series created by Joss Whedon and his brothers, Zack and Jed. It stars Neil Patrick-Harris as Dr. Horrible, a down-on-his luck supervillain, Nathan Fillion as his nemesis, Captain Hammer, and Felicia Day as the girl of his dreams, Penny. Originally available for viewing on the web at www.DrHorrible.com, you can now download it on iTunes. A DVD release is forthcoming, although no date has yet been announced.