D.U.C.K.burg - Fan site with articles, interviews, images, downloads, news, and links.
D.U.C.K.hunt - The most comprehensive web site about Don Rosa.
DuckMania - A Don Rosa fan page with news, presentation about Rosa and art samples.
The D.U.C.K.man - Sections include: Introductions to Don Rosa and his work, biographies of known and less known characters, a guide to the history of Duckburg, a presentation of the clan McDuck, comparison of Duck family trees, and information on story codes.
The Two Worlds of Don Rosa - Compares the different versions of Don Rosa stories.
Versions - A comparison of the differences in a story when it is split into several parts and when it is not, often showing the original artwork and dialog as the artist wanted it.