Here's my list of guesses for now. I'll post a few more times if I think of any more songs.
"Everything's Magic" - Angels and Airwaves
"Here (In Your Arms)" - Hellogoodbye
"The Great Escape" - Boys Like Girls
"1234" - Feist
"Shadow of the Day" - Linkin Park
"Set The Fire To The Third Bar" - Snow Patrol feat. Martha Wainwright
"Everything" - Buckcherry
"Nolita Fairytale", "Hands On Me" - Vanessa Carlton
"Dance Floor Anthem" - Good Charlotte
"Hollywood" - Collective Soul
"Misery Business", "Crushcrushcrush" - Paramore
"Never Too Late" - Three Days Grace
"When Did Your Heart Go Missing?" - Rooney
"Light Up The Sky" - Yellowcard
"Frozen", "What Have You Done?" - Within Temptation
"I Don't Feel Like Dancin'" - The Scissor Sisters
"Love Today", "Grace Kelly" - Mika
"Cab" - Train
"Dashboard" - Modest Mouse
"U + Ur Hand", "Who Knew?" - Pink
"Godspeed" - Anberlin
"Nothing In My Way", "Is It Any Wonder?", "Crystal Ball", "Atlantic" - Keane
"Amazing" - Seal
EDIT: Adding more songs.
"When You Were Young", "Read My Mind" - The Killers
"Nothing Left To Lose" - Mat Kearney
"Bouncing Off Clouds" - Tori Amos
"Ghosts of You" - Chantal Kreviazuk
"Time Won't Let Me Go" - The Bravery
"Better Days", "Stay With You", "Let Love In" - The Goo Goo Dolls
"Good Life" - Kanye West ( Hey, they MIGHT use it...
)
"All Good Things (Come To An End)" - Nelly Furtado
"A Town Called Hypocrisy", "Can't Catch Tomorrow", "4AM Forever", "Rooftops" - The Lostprophets
"Message To Myself" - Melissa Etheridge
"Love and Memories", "Heard The World" - O.A.R.
EDIT 2: Last one, really!
"Ruby" - The Kaiser Chiefs
"The Riddle", "World" - Five for Fighting
...this must be the longest song guesses list I've made in forever. Sorry about the size of it, everyone...