For a six year old - a Wii or a computer?

Get him a computer. The wii will play games and have email but in the end you can do a million times more things with a pc. Alot of the same games can be obtained for a pc that you can get for the wii. The wii will only do email with others who also have a wii, messaging is also confined to users who have a wii. Web browser function is not yet fully functional for the wii. Wii games so far have not been great, the interaction with the games is cool and new but the game content has been lacking for the younger audience. If you want something that can do every one of the functions your refering to i'd stick to the computer. Otherwise the psp may have a usb keyboard soon and you can do mp3's email, web search, games etc.