One of the best things about the show is its soundtrack, and just as the story has recurring themes, so too does the music. Each character has their own unique tune, a tune that can be tweaked for sad scenes, action scenes, or epic scenes.
If you're a real LOST whiz, you'd be able to hum the character's tune before listening to the mp3s below.
JULIET - this theme is what made her death scene so memorable
DESMOND and PENNY
JIN and SUN
and... the best....