Websites for kids which include: Animals, The Arts, History and Biography, Literature and Languages, Mathematics and Computers, Reference Desk, Sciences, Social Sciences. Also included are sites for parents, caregivers, teachers and others. A pretty complete list.
Read about this site in SLJ last month. Great site where all search results are educationally approved. Also, you can divide your search between websites and journal articles. EC
Contains historical texts but also links to many other primary sources and websites. Information on history - ancient, medieval, modern, East-Asian, Islamic, women's. Some links didn't work but the site is massive.