These are some of my impressions of this beautiful city:
 

View from the Rhine Modern Architecture
Schlossturm The Gehry Buildings
Hafen Rheinufer Promenade
The Old Town The River Rhine
Typical Building Typical Building
River Shore on a Winter Afternoon Rhine Tower and Rheinknie Bridge
Rheinturm View of Tower and Bridge
Benrath Castle Benrath Castle
Benrath Castle Benrath Castle in Winter

City Guides:

bullethttp://duesseldorf-today.de/cityguide/stadtrundgang/index.shtml
bullethttp://www.duesseldorf-tourismus.de/
bullethttp://www.duesseldorf.de
bullethttp://duesselgo.de/
bullethttp://www.germany-tourism.de/e/metropole_duesseldorf.html
bullet http://www.deutschland-tourismus.de/top_reiseziele/content_tlstadt-id1071.html
bullethttp://cityguide.max.de/cityguide/duesseldorf

More Links:
bullethttp://www.virtualtourist.com/m/69e51/1078a/ (Düsseldorf Tips)
bullethttp://www.schwann-online.de/gelbeseitencd/JSVhome.asp (Map of Düsseldorf - Stadtpläne)
bullethttp://www.duesseldorf.de/stadtpanoramen/index.shtml (360° panorama pictures from Düsseldorf, just click on the pictures to sample the view!)
bullethttp://www.duesseldorf-today.de/special/duesseldorf-sehen (Take a virtual walk through the city!)
bullethttp://www.duesseldorf-web.de/ (News, links, entertainment, etc.)
bullethttp://www.zollhof.de/camera.htm (New architecture in Düsseldorf)
bullethttp://www.flyingmonk.com/germany.html Photos of Düsseldorf and Germany
bullethttp://www.dw-world.de/ Germany news
bullethttp://www.rp-online.de/news/lokales (Local news)
bullet http://www.duesseldorf.de/europa/ (Europabüro Düsseldorf)

@ Katja Maue