Deutsch Welle is a German news service that offers significant German language learning resources. These are for older students, probably best for teens and adults. The main modules are very much like a traditional language course, focusing on grammar, conjugation, and so on. However, they have many different types of offerings, including Mission Europe, which is a series of podcasts and exercises following a crime-thriller storyline. Mission Europe is available in German, Polish, and French, and has both English and foreign language components.
BBC has a fairly extensive selection of German options. including material for children, teens, and adults. There are videos, games, and audio. If you are not familiar with BBC, it is the British Broadcasting Corporation, and thus much of the English content is with a British accent. This shouldn't be too much of an issue for German language learners, however.
Deutsch-Lernen has several free, online grammar exercises. No audio that I could find.
TONS more resources HERE. However, I have not evaluated the links on this particular site...
Oodles more resources HERE. This is from the University of Michigan, but again, I have not evaluated these links.
For print resources, also consider the magazines Das Rad and Schuss. Das Rad is considered a beginners level magazine, while Schuss is more advanced. Both appear to come with two audio cd's as well, and access to related websites.
Duolingo. I've only played with it a little bit, but it seems fairly easy to use, and is interactive with immediate feedback.
Check out these additional foreign language posts: