Obryn
Hero
Also, Poul Anderson's [ame=http://www.amazon.com/High-Crusade-Poul-Anderson/dp/0743475283/ref=sr_1_1?ie=UTF8&s=books&qid=1220224673&sr=8-1]The High Crusade[/ame].Let's not forget the Guns of Avalon, but that might be a little too old school for many younger readers.
Remember, though, that in the 60's and 70's, some mixture of sci-fi and fantasy was pretty much expected. In the 80's, it was perfectly acceptable and still pretty cool.
The 90's and 00's have more sharply separated Sci-Fi and Fantasy. Though there's quite a market for modern-day fantasy like The Dresden Files and most everything by Neil Gaiman, you usually won't see lasers & dragons in the same novel anymore.
I still love an oldschool mixture of sci-fi and fantasy, like the background for the Wilderlands setting, but it's not really where the center of fantasy fiction and gaming is right now.
-O