FVD video downloader for chrome. There is a similar extension for firefox. Nothing for IE except the online options. The chrome extension adds a download box just below the videos that let you choose a couple video formats and mp3. Does that answer your query? You didn't really ask anything.
Web Based, very quick, nothing to install. I use it all the time. Copy and paste url, hit download. http://www.youtube-mp3.org/
Cheers guys, Alki's was what I was after. Other half wanted some songs from Youtube, and realdownload only downloads movies, not MP3's unless you buy the full package.