Your son sounds very much like my DS at that age. I agree with the previous posters suggestions: starfall.net, Magna Doodle, and the Leapfrog magnet toy:.
http://www.amazon.com/Fridge-Words-...4510370&sr=8-2&keywords=Leapfrog+magnetsI think you should just follow your son's interests. While my DS was interested in letters, I bought the Preschool Prep Sight Words dvds, and he loved those. He also really enjoyed watching the show, Word World. Then, all of a sudden, his interest in letters waned, and he switched to numbers/math. Now, at age 4, I think he is probably more advanced in numbers/math than phonics/reading (he is not reading--at least not that I am aware of; sometimes I do not know what he can do until I observe him in his room when he thinks I am not looking :-)
Anyway, welcome! You are definitely in the right forum. I do not post or ask questions often, but I have found this forum very welcoming and helpful.
