I find music a great way to help myself to concentrate on doing things. I find it difficult to just sit somewhere and listen to music like a lot of people seem able to, but if I have it playing whilst I'm doing something else such as designing a website, playing Worms, or anything else that basically takes a chunk of my 100% attention to the music away, I find it just helps me be more productive.
I'm not one of those people who cannot help themselves from tapping a foot or head to music though, and certainly not one of those who feels the need to sing out aloud to the words of a song. A lot of the music that I listen to is orchestrial soundtrack music though, some of which is very inspiring. I work best with that stuff in the background.