I haven't had time to watch more than the first minute and a half or so, but I'm greatly looking forward to checking out Dr. Horrible's Sing-Along Game, Doctor Octoroc's 8-bit tribute to Dr. Horrible's Sing-Along Blog. (I know, that's a lot of doctors in one sentence.) And no, it's not an actual game. You can read more about it here, but I'd suggest just watching it. Looks amazing.