One great way to celebrate Dr. Seuss' birthday is to participate in Read Across America by reading to your child this evening. You can also watch Seuss videos or play games on the Seuss-themed website Seussville.
The secret art of Dr. Seuss by [author, Theodor Geisel] ; with an introduction by Maurice Sendak
Theodor Seuss Geisel by Donald E. Pease
The Gospel according to Dr. Seuss by James W. Kemp
Dr. Seuss goes to war: the World War II editorial cartoons of Theodor Seuss Geisel by Richard H. Minear