Toddlers who have mastered their letters should next turn to phonics. The trick to using the Internet is to make sure you carefully review whatever you are showing your child before you show him/her the website. A large number of websites teaching phonics completely get the proper phonics wrong. One telltale mistake: using "La" for L. Our kids watched the wrong phonics videos for months before the errors were caught.
Phonics Video #1
Phonics Video #2
The huge added benefit of this video is that it teaches sign language, something every child should know.