Iphone,Ipad,Ipod Apps

My son might be 3 years old, but he has his own Ipod Touch, its a 2gn nothing new but he loves it, I buy apps all the time and get him movies, Some apps I'll recommend are the Thomas & Friends , Games,Puzzles,Reading,Painting what else can you ask for?? and they are not expensive at all.I think my son is to young to play the chuggington ones, he likes them but you have to complete things to go to the next level etc.