Listen to YouTube dot com is a new service which lets you grab the MP3 audio from any YouTube video clip and download it as a file to your computer. Just copy the video’s URL address, paste it into the box, hit the Go button and in a few moments out pops your MP3 audio file ready to download.
There’s a choice of Standard and High Quality capture and the whole process is very fast. You will need to accept a lot of in your face advertising of course, hence the free bit. Nevertheless, it’s definitely bookmark worthy.
ListenToYouTube.com is the most convenient online application for converting YouTube flash video to MP3 audio. This service is fast, free, and requires no signup. All you need is a YouTube URL, and our software will transfer the video to our server, extract the MP3, and give you a link to download the audio file.
A new similar site: http://listentoyoutube.us. Seems to have more qulity options.
I like http://www.convert-me.net (i think is without limitations/big files allowed)