Here is one link
(LiveMocha)for any language that you ever wanted to learn.
You make exercises, both written and audio (so make sure that you have a microphone) as fast as you want/can and they are reviewed by native speakers of the language, which makes for good feedback. It is also free. Personally I cannot find the time to do more with this site, as I am a registered user. That is also where the affiliation ends.