Maybe this is not completely on-topic, but checkout Voxound: www.voxound.com, they built a great online service as well as a desktop software (their main produc

Maybe this is not completely on-topic, but checkout Voxound: www.voxound.com, they built a great online service as well as a desktop software (their main product), which helps you tag / classify all your music. It is truly useful and it doesn't violate any copyright laws. I thought about them because of the quote from Mark Piibe in the article: “We think services like Grooveshark offer great music discovery options for fans,”. Voxound is an awesome music discovery tool. Disclaimer: I am not related with Voxound, I just think they have a really good thing going on, and they only recently started.