Artemis Fowl rules! My 12 year old likes the Ranger's Apprentice books, also Hiccup the Viking, Redwall, the Shadowmancer series, Mortal Engines, The Edge Chronicles, Alex Ryder, the Fire thief trilogy by Terry Deary, Spiderwicke,
My other boys liked Garth Nix , the ones with the days of the week, anything by Robin JArvis, Cliff McNish, Broken Sky, Phillip Pullman, THe Diamond brothers (Anthony Horowitz) The Windsinger books by William Nicholson, Famous Five (yes really), Series of Unfortunate Events, Bartimaeus Trilogy, Septimus Heap.
Artemis Fowl books are the best books that I have come across for boys this age, I have been buying them since they were first published and all my kids have loved them. I really liked Windsinger books, as well. Diamond brothers are hilarious and a nice change if your DS likes mystery (sort of) books.