One of my favorite features of Bloggingheads.tv is that you can play back their videos at 1.4x speed. This lets you listen to an hour long dialog in about 43 minutes and also has the interesting side effect of making people sounds smarter. The player resamples the audio so that the participants don't sound like chipmunks.
You can control the playback speed in Mplayer using the "[" and "]" keys make mplayer resample the audio with the af=scaletempo flag. If you add the flag to ~/.mplayer/config it will do this automatically. This is great for podcasts and "talking heads" programs where you're interested in what is being said and don't particularly care for emotional content.