I usually do ambient music or downtempo electronic stuff when I really need to concentrate on my literature homework. Brian Eno is a big favorite of mine for study music. Otherwise, if it's something during which I can multitask fairly easily (like linguistics), I usually put on an album I'm thoroughly familiar with, or some more progressive/"busy" music like early Genesis or trance.
depends on mood- if i'm feeling inspired, mozart's requiem or st. John passion pump me up. If i'm having trouble focusing, they distract me - for that, eno ambients or baach or liszt piano pieces. Or the Dead- drums/space open up your mind like nothing else (too bad mickey hart went in a weird direction- I can't get into birthing music no matter how hard I try)
Can't listen to music with words when I read, write or program. Tho I find that inspiration can come with intense/creative passages in music, or sustained dreamy soundscapes. So I mostly listen to 60's John Coltrane, Mingus, 1958-1974 Miles Davis, or electronica like Boards of Canada, Explosions in the Sky, Fennesz etc.