What to get a 9 year old boy for Christmas

Today another mom asked me what I was getting my nine year old for Christmas, because she needed some ideas for her 8 year old boy.  Well, once I thought about it, turns out I hadn't actually thought about this yet!  I have not even asked him what he wants!  I had no answer to give her, but I did suggest some things I know he likes. 
Toys like Bakugans, Bionicles, legos
book series he enjoys: Percy Jackson (the Lightening Thief), 39 Clues, The Edge Chronicles.  (the cheapest place to get these books are through your kids scholastic order they bring home from school.  You can talk to your teacher about keeping them a secret)

So, I ask you what would be some good things for 8 &9 year old boys.  Turns out I could use some suggestions my self!

I did get them a Wii Fit Plus at Sam's club for 84.08 (that was the cheapest I could find it)  I also got one of the Toy Story lego sets there for $39.