Bucherkinder.de - a German website with descriptions and tips on the latest German children's books (in German)
Kinder und Jugendbuchportal - Goethe Institut portal on children's literature. (in English)
Kinderbuch-Couch - an online magazine about German children's books (in German)
Rezensionen und Empfehlungen - from the Frankfurter Allgemeine Zeitung (in German)
Reviews from der Standard (in German, from Austria)
International Children's Digital Library - eBook versions of children's books in many world languages.
Schoenhof's Foreign Books - a bookseller with distribution centers in Chicago and Skokie, IL.
For German-language comics, consider the Goethe Institut's page.