There are some good tips here:
The 4 Hour Work Week
Listen to the interview thingy. I really liked the idea of putting an autoresponder that just says that you will not check emails excpet for certain times. To be honest, its a really big relief rather than a nagging feeling that you've got to check email, something importnat might have happened, I've to check email. It's like, he said, a rat with a cocaine pallet dispenser.
Enjoy!