TEACH HIM PIANO!!!
seriously, you need to start your kid on a musical instrument, the sooner the better(it will blow his mind). also start on spanish or french or somethin close to english as soon as you can(as soon as he has a firmer grasp on english). him knowing how to type to his mom at 3 is amazing.
but ya seriously, make sure he gets into music, if he can already understand language this well, especially this early in life, he should do good in the music world. and studieds have found that people who know more then one language are in general faster thinkers at everything. and i would really start him on piano and not another instrument because you get the widest range of keys in front him with a more direct approach then other musical instruments(not to mention how many girls hes gonna impress later if he gets good)