The May 7 WashingtonPost.com has an article on kid-friendly (i.e., filtered search). The article includes reference to both several services intended to protect children from inappropriate content while searching.
The article included a reference to RedZee – a service that was new to me. This site offers both a directory and search service. The site appears to be supported by keyword triggered ads.
Developmental Psychology, a prestigious APA journal, has a collection of articles on Children and the Internet in Vol. 42. The journal is making this collection available to the public – so download the pdfs if you collect material on this topic.
One study (Jackson, et al) reports on the Internet and achievement of low-income families. Internet use was found to be correlated with higher standardized test scores.