If you haven't watched it, then what the hell are you waiting for?
Unfortunately it is no longer available for free, so all you hardcore Whedon/Fillion/Harris fans are just going to have to pay for it or. . . *ahem* piratethatsuckertogetyourfix. I have done the latter, but rest assured I will be purchasing the DVD with all it's glorious extras. This is too awesome not to support.
What is it, you ask?
It's a musical. About a super-villain (Dr. Horrible (NPH)) and his arch nemesis (Captain Hammer (Nathan Fillion)) and his love interest (Penny (who is played by the girl from the Guild)). And it's awesome.
So awesome that I have had songs from it stuck in my head since it's arrival on the scene. So awesome that it's affecting my dreams. So awesome that I watched the third act countless times so that I could type up the lyrics (at the time of me doing this, they were nowhere to be found. If you want a copy, let me know. . .). So awesome that I, too, want to hold a PhD in Horribleness. What the hell am I talking about, you ask? Better watch it!