The website of a German professor. She has oodles of information, worksheets, games, tips, etc. dealing with the German language. I find this site very helpful, especially when I need to present information to kids in a different way.
The German government's home page. It's in German, but there is an English link, as well as the "Leichte Sprache" ("Easy Language") link, which simplifies the language somewhat for students of the German language.
This site is run by a small, but devoted group of linguists and language geeks who want to re-present English (Anglish) as it once was before the Norman invasion of 1066 flooded the language with a plethora of Latin and French words. Anglo-Saxon ftw (if anyone says that anymore)! Anyway, there is an Anglish dictionary, and a list of works that they have translated into Anglish. I have a hard time following it, but it's interesting.....
A cornucopia of information! This site, sponsored by the University of Michigan, offers students a wide variety of services: vocabulary lists, verb conjugation sites, grammar tutoring, information about German pen- and e-pals, and much more. I'm not just posting this because I'm a Wolverine......:)
A very helpful site! Created by the University of Iowa, this site offers files of the different German sounds. There is even an anatomical diagram that shows you how to make the different sounds. It's in German, but you can navigate it easily.
German music videos, that is. You can go here and watch current German music videos. The videos are updated, and the content is completely safe (this is a site that tries to market Germany's culture, so there is nothing inappropriate.
You can go here if you want to practice or learn more German (or any other language, for that matter. You can do exercises and submit them to be evaluated by native speakers. You can also receive credits by evaluating works in English submitted by non-English speakers. You can also friend and chat with German speakers. It's fun and informative. I'm dabbling in Italian myself; I am, after all, 1/4 Italian......