CQ magazine does sponsor Under 21 plaques in the CQWW DX test and may do so in the WPX. I know the ARRL DX used to have under 18 plaques (I won it three straight years a while ago). I doubt you;re going to get a new category as the major contests already have HUNDREDS of categories in a contest. There are a number of youth oriented contests out there. LIDfest was one organized by the WWYC last month and was quite humorous to watch unfold on 80 meters and on DXSummit. Their website is www.wwyc.net and a bunch of them are on IRC chat 24 hours a day in the #wwyc room.