Diapers.com has great deals on diapers if you are a "first time customer". Here is a code to receive $10.00 off your first order of diapers or formula PLUS Free Shipping IF you are a first time customer:
Code - GOODSTART10
Total order must be $49 or more for discount and free shipping. Expires 5/31/2011.
See help center on website for details.
I personally only ordered from them one time because their initial promotion savings made it worth it, but after that, their prices were higher than other places (like Walmart & Amazon).