Whether you have your own copies, check them out at the library, or buy a couple from Kohls, here are a bunch of great activities to go along with them....
Online Games and Activities for ALL of the books
A Collection of Activities Submitted by Moms (ABC & 123)
If You Give a Moose a Muffin Activities (Homeschool Share)
If You Give a Mouse a Cookie (Homeschool Share)
If You Take a Mouse to the Movies Activities (Early Elementary)
Elementary Classroom Activity Guide (Elementary level - all books)