+1 on ear buds. i use cheapo walmart ones with my phone. my friend does to but he has that new tiny nano and he clips it to one of his cables. and I've seen some kid on a scoot rocking full cans! thats just awesome.
not a huge fan of speakers myself. cant beat the sound earbuds give ya...
i'm totally surprised this thread isn't filled with "don't do that, thats not safe" comments! haha thats all i get from everyone.. i figure wind noise + exhaust noise = i cant hear crap anyway. policia and or horns cut threw the noise of my earphones.