ABC Blocks link to letters with sounds, photos, and animations for each. Good stuff, but a little slow-paced.
Fisher-Price Toddler Games
This site offers several educational activities for toddlers: Learn your ABC's, ABC's Zoo, Little People Animal Sounds, Learn your Colors and Shapes, Count the Score, and Little People Who's at the Door?
Five Hungry Crocodiles
Learn colors by feeding the right color fish to each croc in this game.