Wow...I'll try to keep this list somewhat short [and I'm only going to list one song by each artist] So, in no particular order:

Tango Til They're Sore - Tom Waits
Ophelia - Natalie Merchant
Back in Black - AC/DC
Runs in the Family - Amanda Palmer
Eleanor Rigby - the Beatles
Lookin' Out My Back Door - Creedence Clearwater Revival
Kodachrome - Paul Simon
Carry On Wayward Son - Kansas
Spanish Doll - Poe
Deeper Understanding - Kate Bush
Sitting on the Dock of the Bay - Otis Redding
Medication - Garbage
Doctor My Eyes - Jackson Browne
Laugh, I Nearly Died - the Rolling Stones
Crawling Back to You - Tom Petty
A Boy Named Sue - Johnny Cash
Pagan Poetry - Bjork
Sleepwalker - the Wallflowers
Operator - Jim Croce
So What? - P!nk
Sex Changes - the Dresden Dolls
Verdi Cries - 10,000 Maniacs
Black and White - Sarah McLachlan
Cold War - Janelle Monae
9 to 5 - Dolly Parton
No One Knows My Name - Gillian Welch
Two Silver Trees - Calexico
Ain't That A Shame - Fats Domino
Howl - Florence and the Machine
Bring The Pain - Missy Elliot
Time and Time Again - Counting Crows
Money Changes Everything - Cyndi Lauper
Hysteria - Muse
Running Up That Hill - Placebo
Breathe Me - Sia
Lucky - Radiohead
Dashboard - Modest Mouse
Walkin' After Midnight - Patsy Cline
the Gambler - Kenny Rogers
King of Pain - the Police
the Boxer - Simon and Garfunkel
Say Aha - Santigold
Stop Me If You've Heard This One Before - the Smiths
Your Dictionary - XTC

Ok, I've just got to stop myself now...I could go on forever.

Beautiful Wish - Seira
Return to the Sea - Sara
Brothers - Vic Mignogna
Open Your Mind - Yoko Ishida
White Destiny - Yoko Ishida
Mother Symphony - Lucia Nanami
Tsukiyo no Marionette - Yuichi Nakamura
Tsukiyo no Violinist - Ikuto Tsukiyomi
Kuro Neko no Serenade - Ikuto Tsukiyomi
Myself - myco
Lost My Music - Aya Hirano
Eternal Snow - myco
New Future - myco
My Song - Takane Shijou
Splash Dream - Lucia Nanami
MY BOY! - Buono!
Kokoro no Tamago - Buono!
Minna, Daisuki! - Buono!
Itsuka wa ROMANCE - Rima Mashiro
Piece of Love - Rina Touin
Star Jewel - Rina Touin
Smoky Thril - Iori
Overmaster - Takane Shijou
Kosmos, Cosmos - Yukiho
Colorful Days - Yukiho
Want You Gone - Ellen McLain
Still Alive - Ellen McLain
Cara Mia - Ellen McLain
Sisshou - Vic Mignogna
True Light - Vic Mignogna
Strawberry Power! - Ichigo Momomiya
Don't Cry - Zakuro Fujiwara
Tsubasa - Noeru
Beautiful Wish - Seira
Legend of Mermaid - Rina Touin
Sakura Kiss - Cristina Vee
TRANCE to Homunculus - Envy, Lust, Wrath, Pride, Greed, Gluttony, and Sloth
Blue Moon - Nana Mizuki
Pray - Nana Mizuki
Meikyuu Butterfly - Nana Mizuki
Black Diamond - Nana Mizuki
Afternoon Tea - Mint Aizawa
Blue Bird - Mint Aizawa
YES! YES! YES! - Pudding Fong
Guilty, Beauty, Love - Vic Mignogna