nano.... mp3 player will get old after a while but you can always do something new with a nano
but.. there is a lot more money in the nano probably, unless you get a REALLY expensive mp3 player
the greatness of an iPod is unrivaled by anything fish related I wouldn't get anything bigger than a 20 GB, although the photo ipods are cool, unless you listen to a LOT of music...but hey whatever
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great man it was worth the money but at the same time I would love a nano tank for my studio over here. it would be a nice start for me to get into having a saltwater tank. but there both really good in the long run at lest from my point in view