i play tons of different stuff for my babies. some personal favorites are the dead kennedys, black flag, frank zappa, isis, de la soul, mac dre, erykah badu, weedeater, buzzoven, the beatles, bob marley, ravi shankar (or world music from wherever my current strain is indigenous to). i like to play more jazzy, upbeat, freeform stuff (zappa, sun ra, magma, minus the bear, etc.) for the sativas and play the slow, heavy, repetitive stuff (hip-hop, sludge, doom metal) for my indicas. my goal is to make the plants feel more at home but expose them to something interesting. sometimes ill take my guitar in the grow room and noodle around too. i can't imagine plants would want to hear music they helped inspire all the time so i try to work in a fair share of non pot induced tunes.
i think someone should do some experiments with an unstable hybrid to see if music has any effect on the prevalence of a particular phenotype within a seedlot. my stereotypical, new age, stoner thinking tells me that it does.
check out masaru emoto's experiments on water crystals for some further reading.