Starfall looks like a great site. Thanks! I just played with my 3 year old and she loves it. She's so excited now she won't go to bed!
I think there are too many comments so far about sending your kid outside or buying physical toys. I think those comments are unrealistic or irrelevant. Of course your kid should go outside but what do they do after 5pm. Sure she has a room full of toys that she plays with. Dolls, toyhouse, legos, paint, clay, etc. But I want my kid to read as well.
Well-made software like this has built a strong desire for my daughter to read at 3 years old. Even reading books to her every night since she was 10 months old has not created as strong as a desire.
There is some great windows software as well - reader rabbit, key skills, and jumpstart. I like the software better than flash websites - for the younger kids you don't have to worry about them mis-clicking on the start menu, back button, etc. Just a minute ago my daughter right-clicked and was sitting at the adobe flash website wondering what to do next.