Quergelesen - reading tips from "Quergelesen," a program on German's children's TV channel KiKa. (in German)
Bucherkinder.de - a German website with descriptions and tips on the latest German children's books (in German)
Must read German children's books - a list of top German children's books (in English)
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)
Arbeitskreis fuer Jugendliteratur e.V. - registered organization in Germany that promotes children's literatur through newsletters, prizes, and fellowships for writers.
Stiftung Lesen - charitable foundation dedicated to reading competency and enjoyment.
Vorlesetag - the annual German Read-Aloud holiday, sponsored by Die Zeit, Deutsche Bahn, and other major organizations.
Alphabet Garten - A Washington-based bookseller of German children's books and DVDs.
International Children's Books - bookseller in Florida sells multiple languages as well as bilingual books.
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.