The other day i was watching a BBC World News technology segment called "Click". Where the interesting topic of games for pre-school children came up. Where basically the game industry market doesn't reach very well.
Here are a couple of offerings online for free games catering towards Pre-Schoolers
1) Fisher Price Link
2) Fun Gooms Link
3) Disney's Club Penguin Link
Since i'm not a parent, nor do i have any form of kids in any capacity, unless i count myself.
Those would be the only limited resources i would know about for the pre-schooler demographic.