Alex Rider - the teenage James Bond. If you haven't heard of it, you will soon as the first novel is shortly out on film.
If you've got 8 - 12 year old boys, I would warmly recommend it, especially if you can't stand Harry Potter but still want your kids to get excited about books. I came across Stormbreaker by mistake late last year, and now every evening at bed time is another chapter - we're just starting the 5th one, Scorpia.
Formula is basically James Bond, except with a likeably dismissive attitude to girls. Well-written, breathlessly exciting, fairly intriguing characters. Second one is a bit slow, but still good.
My only real complaint is that I wish he could come up with slightly more credible motivations for his baddies' desire to blow up/poison/whatever the world, but this is a fairly minor point.