Because sites offering Niconico services are as fun as the site itself, I can’t help but share a particular gem. now i don’t recall who showed me it or where I found it but it’s a very, very useful little tool that has helped me more than I’d care to admit. This site simply allows you to enter the address to a Niconico video and will offer you the ability to download the video as an mp3! Very helpful for remixes or songs that are otherwise hard to find. Quality is great and it’s super easy. There’s also a handy little streaming audio player in case the video takes too long to load for you or you just have problems with viewing Niconico in general, as I often do.
In case you missed it: http://nicosound.anyap.info/
And if you need a little assistance:
EDIT: as of Febraury of 2014 (and well before), Nicosound had closed down for good. We had a good run, guys.