There is awesome and there is awesome... and then there is Dr. Horrible's Sing-Along Blog. I haven't always been the biggest Joss Whedon fan, not since the Buffy days anyway, but this, I gotta say, is something else. I mean really something else. No more words... go check it out.
UPDATE: Dr. Horrible's Sing-Along Blog is, sadly, no longer available as free, streaming video. It has vanished into the ethereal night. However, do not panic, gentle reader, for it is still available on iTunes and will be released on DVD shortly.