I recently joined the German Language Club on Yahoo, a large friendly group of students who help each other in their quest for learning Deutsch. Have a question about the grammar or vocabulary that’s been bugging you for the longest time? Ask those guys a question, and you’re bound to get it answered in no time. Hell, I am a native speaker and even I learn something new occasionally!
Incidentally, some of the posters there use the training materials provided by Deutsche Welle for some group learnings.
Both of those sites come highly recommended if you’re interested in online learning.