In case you don't know it,
Freeman's Mind is a brilliant series of videos, going through the original Half Life with narration of what's going on in Gordon Freeman's mind (thus the name, duh). If you don't know it, be sure to watch it, though it's quite a time sink. New episodes pop up from time to time, but the process is slow unfortunately, and there seem to be some legal difficulties going on right now, so the latest episodes are delayed.
Anyway, on April 1, the author made a one-shot video of Doom Guy's mind which is exactly what it say on the tin. I'd say the narration is easily on par with the infamous Doom comic. (And no, there are no parts 1-6)
Watch it
here.