Miscellaneous
Series in general
The Voice (Celtic Woman) - "The voice" is the call of the forest and of warrior life. I don't know why it came into my head as my personal "theme" for Warriors, but that's what it is.
Great JourneyMove Along (The All-American Rejects) - The song came out around the same time as Dawn, I think. I heard it a lot around when the book came out.
ShadowClan
Aqua Harp (Animusic) - Discovered Animusic around the time of The New Prophecy. This song makes me picture a ShadowClan cat slinking gracefully through a marsh at nighttime.
Characters
Silverstream
The River (Garth Brooks) - (Sorry for video quality; they're apparently diligent about removing just-plain-audio versions of the song and I can't find even one). I thought this fit her love for Graystripe; the song is about following dreams. And then I realized afterward that the whole "river" thing fits her being RiverClan.
Crowfeather
I'm Moving On (Rascal Flatts) - This completely fits him after returning to his Clan after his romance with Leafpool. "Finally content with a past I regret"... "I've been burdened with blame, trapped in the past for too long" fits the romance, and then "I've lived in this place and I know all the faces, each one is different, but they're always the same. They mean me no harm but it's time that I face it: they'll never allow me to change".... WindClan will never think of him differently, he'll always be the cat that ran off with Leafpool.
Sasha
Restless (Sara Evans) - One of my favorites on this list. This song fits her being a wanderer, and once the manga came out it still fit, especially the bridge about wanting to find someone who cares and finding a place to put down roots.
Sol
The Piper (ABBA) - Sol is "the Piper" to the Clans. He came to ShadowClan, and they let him "play their minds away". And "the fear was a weapon in his hand".
Bluestar x Oakheart
If I Never Knew You (John Secada & Shanice) - This is another of my favorites on this list. This just fits their illicit, enemy-Clan romance perfectly: "I never thought that fear and hate could be so strong, all they'd leave us were these whispers in the night... But still my heart is saying we were right..."
Sasha x Tigerstar
Sweet and Wild (Dierks Bentley and Sarah Buxton) - The first time I heard this was in the car, reading the first TigerxSasha manga for the first time. It fits their romance.