A brilliant essay in The New Yorker from Sasha Frere-Jones explains why ringtones are so fascinating:

"The ringtone also teaches us how songs work. Which clip best exemplifies a song? Did the ringtone’s maker select the right bit? Do you even need to hear the singing? Perhaps the part of the song that arouses our lizard brain is the instrumental opening. It may be stranger and more sublime to hear a polyphonic impression of George Michael’s voice than to listen to the real thing one more time. If a song can survive being transposed from live instruments to a cell-phone microchip, it must have musically hardy DNA..."

Clive Thompson agrees, calling ringtones "a curious artform, part metaphor and part metonym: both a version of the thing and the thing itself."