GermanWine.de - Comprehensive, general resource offers an overview of grape growing, winemaking and regions. Also lists a number of wineries. - http://english.germanwine.de/
Edenwines - Offers information on classifications, grapes, A.P. numbers, and regions, including maps. From a UK-based importer and retailer. - http://www.edenwines.co.uk/
Short Guide to German Wines - Schlossadler, a US importer, provides this overview of the regions and the grape varieties. - http://schlossadler.com/guide1.html
VinoNet - A portal to leading wineries, providing general information as well as point-of-sale material to the trade. - http://vinonet.com/
GermanWineEstates - A site for the German wine lover, with tasting notes, vintage reports, reference information and photos. - http://www.germanwineestates.com/
Germanwine.net - Basic introduction to the country's wines and a gateway to a number of high-end producers; maintained by Cellars International. - http://www.germanwine.net/
German Wine Page - Non-commercial site covering the fundamentals: labels, regions, leading producers, grape varieties, history, tasting notes. Thoughtful editorial content. - http://www.winepage.de/