YouTube is full of all sorts of interesting lectures, polemics, diatribes, and other things that could be easily be enjoyed audio-only. If you find some gems on YouTube you'd love to listen to while commuting or working out at the gym, don't skip over them because you can't YouTube on the road. ListenToYouTube is a simple web-based application for pulling the audio out of a YouTube video and converting it to MP3. The service is free and simple: you plug in the URL for the video, it grabs the audio, you download the MP3. Oh, and it works quite well for music, too.
Found at LifeHacker