This is why I love the Internet. Without it, I would never have heard about what is quite possible the most awesome fan-made game modification ever. In fact, it probably wouldn't have gotten made in the first place.
And that would have been a damn shame.
Some guy decided to rerecord all of the sound effects from Half-Life 2 and replace them with...
His own voice.
That's 1,327 sound files, according to his YouTube video description, that are now some dude doing sound effects with his microphone.
This is one of the most entertaining YouTube videos I've seen in quite some time. Major props to this guy.