On the site you can watch live TV, listen to German radio, and read the news from a German perspective.
The parts of the site which interest me the most are the language learning and culture pages.
The teaching and learning sections offer a variety of interactive German courses for learners of all levels and resources for teachers, too.
The culture section is an invaluable tool for any Germanist. I particularly like the podcasts and something I've blogged about before, German word of the week.
It is impossible to do this site justice in one blogpost but I really would recommend that any teacher of student of German takes some time to have a look at how good it is.
Did I mention that using the site is totally free?
There is also a weekly quiz where one lucky participant can win an ipod.
What more could you want?