I bought my 11 year old a CZ 452 Style.
It's quite a bit more expensive than most other .22's. The nickel finish and synthelic stock appeal to him and the added weather resistance is a bonus. Its very well built and extremely accurate.
Even though its a full-sized gun it fits my boy well (he's of average size compared to his peers). I put a weaver K6 on it, because it wasn't on anything else. With that gun, he's guaranteed instant death (head shots consistently) for small critters around here.
The added expense ensures that he has a quality rifle that he will be able to use for a long time and perhaps pass on to his son some day.
His youger brother is 9 and uses a 10/22 with an aftermarket kid's stock. I wouldn't recommend a semi-auto for kids, but mine has learned not to "play".