I love playing good classical music when I’m trying to think. Notice I don’t claim to actually succeed at thinking, but I do succeed at listening to music.
It works best if you can find something capable of doing it consistently. It seems different on every distro I try. So here we are on Debian Lenny AMD64, and the desktop is KDE. No GNOME stuff, thank you. With my favorite, Xine, it kept locking up. I also tried Kaffeine, but relying the Xine engine, it did the same thing. I also tried Mplayer/Kmplayer. That would skip and hesitate, as if it couldn’t buffer enough. Of course, Kscd has no sound at all, so that’s pointless.
Finally, I tried Amarok. Immediately it did all the things it was supposed to do, and played my CDs just dandy. It’s a keeper.