I agree with what has already been said! While DS6 has always been far ahead in both, it was reading (at 2) that shocked everyone. Very few people other than teachers realized that things like 1-1 correspondence and basic addition were extraordinarily advanced at that age, too. Since he could constantly practice reading on his own, he skyrocketed in reading, to the point where he was in 2nd grade math at 5.5 but tested in at 9th grade reading comp. (and read the HP series--the scary things went right over his head).
However, now that he's doing "fun math" (what he calls algebraic equations and mult/div), he's "catching up" in math and moving faster in that than anything else. At 6.25, he's approaching 4th grade in EPGY math. NOW, we hear more buzz about his math skills than his reading skills.
Your son is still young as a reader, so there's certainly nothing to worry about. You are definitily right, though, that when he does develop the reading skills, his world and knowledge base will suddenly take off with all that he can devour!
Meanwhile, the best reading program I've found online is abcreadingeggs.com. They're doing 5 week free trials right now, and my 29 month old loves it when we dabble in it. It claims to go through "2nd grade", so you'll likely get your $ out of it with a 6 month or 1 year subscription. Plus, it's just entertaining and fun for your son's age group.
