These people remade the first two King's Quest games with VGA graphics. While the remake of the first one is essentially the same game with a different interface, the second one has been mind-blowingly altered. The puzzles all make sense now, there's a much deeper plot, and there are several references to the other games in the series. Along with the music and voice packs, this borders on being as good as the sort of thing one might normally pay money for.
Edit: Interestingly enough, the voice of King Graham is by the same actor as it is in the CD-ROM versions of King's Quest V and VI.
These guys are following up on AGDI with a remake of King's Quest III. They're hoping it'll be out in the fall.
And over here is fan-made King's Quest IX, which will be released in three parts, each of which will be roughly the size of King's Quest VI. If the story is half as deep as the stuff AGDI added to KQ2, I can't wait.