Wort der Woche (Deutsche Welle)

Deutsche Welle's Wort der Woche is a little-known but great resource for the history behind a lot of German words and expressions, which after almost a decade has amassed quite the large number of terms. Arschkarte (the red card in football/soccer) is a particularly good one. Apparently it's so named because before TVs had colour the referee had to carry the two cards in different places so the spectators could know which card he had drawn, and the red cards were kept near his Arsch.

Each one of these also comes with an mp3 matching the text exactly, so they work great for dictation/transcription.