Dr. Horrible's Sing Along Blog came out a few months ago. At the time everyone told me it was crappy (everyone on Defamer, anyway), and I believed them because I didn't know what it was about. It is apparently all about AWESOME. It's got Neil Patrick Harris and Nathan Fillion (new celebrity boyfriend, by the way), and Joss Whedon was involved with it somehow...and it's a musical. A ROCK musical. A rock musical about EVIL and SUPERHEROES and LOVE!
Anyway, NPH is hilarious and has a great voice, and Nathan Fillion is a good sport and handsome to the point of making me angry about it. And the music and lyrics are good too. I highly recommend that you watch it - it's only an hour long, and it's very conveniently on Hulu right now if you want to check it out.
UPDATE: I included a link to the musical over under Favourite Links. Click on "Dr. Horrible's Sing Along Blog Page", natch.