Owners of a current Unofficial Guide (including the "With Kids" version) receive a great discount on a one-year subscription to TouringPlans.com.
To get this discount, click the Own a current Unofficial Guide? link while subscribing. (See below; this link might not appear until after you've entered a Username).
Have your book handy because you'll need to answer a couple of questions from the book in order to get the discount.
Note that you only get one book discount per purchase and that the book must match the subscription in order to get a discount. By this, we mean that the Walt Disney World book only gets you a Walt Disney World subscription discount, the Universal Orlando book gets you only a Universal Orlando subscription discount, etc.