On this site you will find a little more about Read Across America Day, including some fun activities: NEA's Read Across America
This post from Shannon's Technology Rocks! Seriously blog- (And YES, it seriously does rock!!) has TONS of Dr. Seuss themed games, activities, & lessons.
Seussville offers some fun online games for students.
Seussville Story Maker helps students create Dr. Seuss like stories.
Scholastic has lesson ideas using Dr. Seuss books.
Can't celebrate Dr. Seuss' birthday without a little Green Eggs and Ham!!
Green Eggs & Ham Interactive Read-Aloud Video
Technology Coaches Michelle Fikac & Elizabeth Garvic created this amazing resource- The Tech in the Hat! All of the activities are centered on technology integration using the works of Dr. Seuss!
This is an example of one of the activities:
Another exciting idea would be to connect your class with another class via Google Hangouts (kind of like a Skype session). You could read a Dr. Seuss book and then discuss with the other class.