Have you taken a few German courses before or are you new to the language? Before you pick out which online German Lesson to take, you can test your comprehension on language-learning websites like those offered by the British Broadcasting Corporation (BBC).
Listen to online German Lessons on the BBC. The BBC offers a variety of German Lessons, such as "German Steps" with games and slideshows online, so you can learn German on your own time. "Talk German" has online activities and a TV series that you can stream. If you are traveling to Germany for business, you should try "Make German your Business" as it covers work and travel vocabulary.
Listen to online German Lessons on Deutsche-Welle. Deutsche-Welle, a German radio and television broadcasting corporation, offers a variety of interactive lessons, TV programs and radio programs for German learners. "Deutsch Interaktiv" is free and covers beginner through advanced levels. "Radio D" streams the day's news in German, but at a very slow pace designed for non-native German speakers.
Listen to German podcasts. A large number of German courses exist as podcasts that you can stream in case you cannot download them. Deutsche-Welle offers a podcast called "Deutsch: Warum Nicht? [German: Why Not?] that covers the life of Andreas who works at a hotel. Other German language podcasts that you can stream include "Language Addicts: Learn German Vocabulary" that focuses on learning nouns and "One Minute German" offered by Radio Lingua.