I found 3 medals that aren't in the list.

Bulltrue - Killed the opponent in the act of a sword lunge. (Also the dumbest name for a medal ever)
http://i41.photobucket.com/albums/e294/Koitiz/bulltrue.jpg

Killed Juggernaut - Kill the juggernaut in a juggernaut game.
http://i41.photobucket.com/albums/e294/Koitiz/JuggMetal.jpg

Skyjacker - Board a flying vehicle. (I dont have a picture for this one)

Well everybody, this is my first forum, so don't be surprised if I don't do it right. Anyway, this one will be about the weapons in Halo 3, because I know that there are quite a few things people want to discuss about them.