Recommendations needed for a voracious 10-year-old sci-fi/fantasy fan!

Details from my inbox:

I wonder whether you would be willing to ask your readership to help me choose some great Christmas gifts for my son, who is 10, a voracious reader and quite choosy about what he reads. He is a computer & video game nerd, likes fantasy and sci-fi and particularly enjoys novels where the main character is a young genius. He has enjoyed Evil Genius, Artemis Fowl, Bartimaeus, and everything by Brian Falkner (Brian Jack etc). He loved David Eddings' entire oeuvre, and we are trying to find other fantasy writers who write epic series without any sex or extreme violence, but that can be tricky. He doesn't like spy novels or mysteries. He's read (or rejected) everything that I and my local kids' bookseller can come up with, so we need some fresh ideas!

Go crazy!