After reading the wikipedia article, Ive come to the conclusion that Pink noise is like white noise only a little gayer.
. ohhh.. I kill myself..No offense to anyone. But getting back to what kind of tracks. I like Mozart, Vivaldi and some Beethoven. I'm also experimenting with movie soundtracks. You have to keep it all at a ridiculously low volume though so you can just barely hear it.
It seems that there are theories about how sound waves of particular types of music can help in the concentration process and arguments against it as well.