This webcomic is one that a few people either shared with me or otherwise linked to, and it's simply fantastic. A short while back, someone linked this particular comic in the comments at Wolf; interestingly, YouTube actually added this very feature shortly thereafter.
I'm just waiting for Google to add an audio preview to Blogger comments - then perhaps the world will quickly become a better place for us all...
On the flip side, this one might be even funnier:
It's worthwhile to check out the actual strips; the mouseovers are half the fun at xkcd.