I have here a tool that converts YouTube music into MP3. http://www.flockee.com/static/youtube-to-mp3/?category=... is the best tool as I am searching for the best converter on internet. Its cheap because it 100% free. Also, the instruction is easy. Just paste the URL of the chosen music video and in just a couple of minutes, it will be converted.
You should try using ConvertMagic.com - Their free online file converter is great for converting mp3, mp4, wma, wmv, avi, mov and all of the popular audio / video file formats are supported. There is no limit on the number of free file conversions and no software to download. Converting music for my ipod is simple with their online file converter service.