Misguided Ghosts - Paramore (Brand New Eyes)
Born For This - Paramore (RIOT!)
Here We Go Again - Pixie Lott (Turn It Up)

alexandra burke - the silence, dumb.
leona lewis - outta my head, take a bow.
the saturdays - one shot & chasing lights & fall
rihanna - fire bomb, good girl gone bad.
pink - bad influence

Britney Spears - Toy Soldier
Lady GaGa - Dance In The Dark
Girls Aloud - Miss You Bow Wow

The Saturdays - One Shot, Wordshaker, Fall, Keep Her

Beyonce - Scared of Lonely

Ke$ha - Animal

Plan B - Writing On The Wall, Traded In My Cigarettes, Free

Spice Girls - Love Thing.

http://www.youtube.com/watch?v=BEkki8CqgvU

No idea why they didn't just release it as the 5th single from Spice. It deserved to be a single. Mind you every track on that album could have been at the time.

Lady Gaga - The entirety of The Fame Monster that was unreleased, especially Dance In The Dark.

Sugababes - No More You, Thank You For The Heartbreak and She's A Mess from Sweet 7.

Paloma Faith - Play On.

Rihanna - Breakin' Dishes

Florence + The Machine - Howl and Blinding.

The Saturdays - One Shot

Alexandra Burke - The Silence

Britney Spears - Get Naked (I Got A Plan), Out From Under, Shattered Glass and Kill The Lights.

Cure - Plainsong (Disintegration)
Cure - Disintegration (Disintegration)
Cure - Push (Head on the Door
Kirsty MacColl - Soho Square (Titanic Days)
Fleetwood Mac - Silver Springs (Rumours) - I'm not sure if it was later released by Stevie Nicks but it's definitely the best off Rumours in my opinion (even if it was kept off the original release).

Rihanna - Good Girl Gone Bad, Breakin Dishes, Fire Bomb
Sugababes - Crash And Burn
Cheryl Tweedy (as much as I dislike her and her music usually) - Happy Hour
Jay Sean - Lights Off, War, All or Nothing
Mariah Carey - Side Effects, Migrate
Lady Gaga - Paper Gangsta
Leona Lewis - Take A Bow, Outta My Head, Can't Breathe, Alive, Misses Glass
Beyonce - Radio, Scared of Lonely, Get Me Bodied, Hip Hop Star
Destiny's Child - Stay, Hey Ladies, Temptation, The Story of Beauty, So Good, Happy Face, Brown Eyes
Alexandra Burke - The Silence
The Saturdays - Lies, Fall, One Shot,
Christina Aguilera - Infatuation, Walk Away, Soar, Oh Mother

I think this was released, it was a tour video though...video

Paloma Faith - Play on, Stargazer
Pixie Lott - Here we go again, Rolling stone
The Saturdays - Lose Control
Adam Lambert - Sure fire winners, Fever
Diana - Hit
Cheryl - Stand up
Florence - Howl
Kesha - Backstabber, Kiss N Tell
La Roux - Tigerlily (But not being released)
Lady Gaga - Dance in the dark, Summer boy
Lily - Back to the start

I could go on and on!

Biffy Clyro - Born On A Horse
La Roux- Growing Pains
Alicia Keys- Wait Til You See My Smile
Eliza Doolittle- Missing
Duffy- Scared
Adele- Right As Rain
Robyn- Dance Hall Queen
The XX- Stars
Amy Winehouse- Me & Mr Jones
The Black Keys- Next Girl
The Killers- I Can't Stay
Paolo Nutini- No Other Way
Daniel Merriweather- Cigarettes
Plan B- The Writings On The Wall

Just about everything on Marina's and Florence's albums

Just a few off the top of my head:

Christina Aguilera - Infatuation, Underappreciated, I'm OK (all Stripped)
Florence & The Machine - Girl With One Eye (Lungs)
Kate Voegele - Sweet Silver Lining (A Fine Mess)
Lady Gaga - Speechless, Teeth (The Fame Monster)
Leona Lewis - Alive, Outta My Head (Echo)

Anastacia:

Rearview
Maybe today
Underground army
I call it love
How come the world won't stop

Kelly Clarkson:

Long shot

Now you're talking... TUNE

Some off the top of my head:

Saturday night divas - Spice girls
Dance in the dark/ Summerboy - Lady gaga
Watch me go/ Waiting - Girls aloud
Put it in a love song - Alicia keys

Far too many Kylie tracks to mention, but a couple include
Sensitized
Burning up
Right here, right now

Leona - Cant Breathe! Should have been lead single off new album

Beyonce - Smash into you & Radio
Xtina - I am & WooHoo
Madonna - Sky fits Heaven
Pink - 18 Wheeler

And cant believe nobodys mentioned...

Destinys Child - Through with love. Their best song ever I think!

Will come back once I've thought of a few more!

[quote=piggin26;43334515]Cure - Plainsong (Disintegration)
Cure - Disintegration (Disintegration)
Cure - Push (Head on the Door
Kirsty MacColl - Soho Square (Titanic Days)
Fleetwood Mac - Silver Springs (Rumours) - I'm not sure if it was later released by Stevie Nicks but it's definitely the best off Rumours in my opinion (even if it was kept off the original release).[/QUOTE]

'The Chain' off Rumours is one of the best album tracks ever too.

Alexandra Burke:
The Silence
Good Night, Good Morning
Overcome
Nothing But The Girl
Britney:
Out From Under
Quicksand
Shattered Glass
Carrie Underwood:
Flat On The Floor
Quitter
Cheryl Cole:
Stand Up
Christina:
WooHoo
Desnudate
Glam
Demi Lovato:
Everytime U Lie
Quiet
Solo
Diana Vickers:
N.U.M.B.
You'll Never Get To Heaven
Notice
Eliza Doolittle:
Moneybox
Rollerblades/Mr Medicine (whichever isn't next single, some rumours say RB, some say MM)
Ellie Goulding:
This Love
Florence & The Machine:
Howl
Jordin Sparks:
Freeze
God Loves Ugly
Kate Nash:
Mariella
Paris
Katharine McPhee:
Open Toes
Katy Perry:
ET (could be released after TD and Firework)
Self Inflicted
Peacock (could be released after TD and Firework)
Pearl (ditto ET and Peacock)
the rest of her Teenage Dream album
Kelly Clarkson:
Addicted
Gone
Don't Let Me Stop You
Ke$ha:
Animal
Blind
Dancing With Tears In My Eyes
Party At A Rich Dude's House
Kylie:
Aphrodite
Too Much
Lady Gaga:
Dance In The Dark
Teeth
Speechless
Paper Gangsta
Brown Eyes
I Like It Rough
Starstruck
Laura Marling:
Made By Maid
Leona:
Outta My Head (crazy she didn't release, she could have had a number 1, would've appealed to a wider audience)
My Hands
Whatever It Takes
Yesterday
Lily Allen:
Knock Em Out
Miley:
Liberty Walk (could be released after Who Owns My Heart)
Every Rose Has It's Thorn (ditto LW)
Miranda Lambert:
Only Prettier
Pixie Lott:
Here We Go Again
Professor Green:
Oh My God (ft. Labrinth) (could be released after Monster)
Kids That Love To Dance (ft. Emeli Sande) (ditto OMG)
Rihanna:
Breakin' Dishes
Good Girl Gone Bad
Rockstar 101
Fire Bomb
Saturdays:
Karma (could be released after Higher)
Chasing Lights
Fall
One Shot
Wordshaker
Selena Gomez:
I Won't Apologize
I Got U
The Way I Loved You
Sugababes:
Thank You For The Heartbreak
Miss Everything
Crash & Burn
3oh!3:
Deja Vu (could be released after Double Vision)

As you can see, not many

Miley Cyrus' cover of 'Every Rose Has It's Thorn' is just about one of the worst musical atrocities ever committed.

Off the top of my head....

Sugababes - Virgin Sexy
Pet Shop Boys - The Theatre
Melanie C - You'll Get Yours
Robbie Williams - Karma Killer
Michael Jackson - Privacy / Is It Scary / Dangerous
Kylie - Butterfly
Natasha Bedingfield - Wild Horses / (No More) What If's
Janet Jackson - Trust a Try / This Time

New Order - Vanishing Point
808 State - Flow/Coma
Roisin Murphy - Dear Miami
Nirvana('s cover of) - Where Did You Sleep Last Night?
Portishead - Roads

Plus a ton more no doubt, oh and you could include every single track on; Aphex Twin - Selected Ambient Works 85–92, no singles from that iirc.

Alexandra Burke
Nothing but the girl
the silence

Diana vickers
n.u.m.b
four leaf clover

any jason derulo songs not released

Oh God, what a can of worms.

I'll stick to one artist at a time I think, starting with Madonna:

Madonna - I Know It
Like A Virgin - Over And Over
You Can Dance - Spotlight
Like A Prayer - Til Death Do Us Part
I'm Breathless - Back In Business
Erotica - Bye Bye Baby
Ray Of Light - Skin
Music - Impressive Instant
Hard Candy - She's Not Me

The Jam

To Be Someone
Billy Hunt
It's Too Bad
The Place I Love
Private Hell
Saturday's Kids
But I'm Different Now

The Saturdays:
Fall, Chasing Lights, Keep Her, Set Me Off, Vulnerable, Here Standing, Loose Control, Wordshaker,

McFly:
Bubblewrap, Little Joanna, Walk In The Sun, Everybody Knows, Corrupted, POV, The End, Not Alone, Too Close For Comfort

Westlife:
The Easy Way, Something Right, Catch My Breath, Turnaround, Written In The Stars, No No, Shadows, Where We Are, Sound Of A Broken Heart, I'll See You Again, As Love As My Witness, I Want To Grow Old With You, Imaginary Diva, Walk Away

Girls Aloud
Love Is Pain, Girls Allowed, Close To Love, Fling, Black Jacks,Graffiti My Soul, Deadlines & Diets

Boyzone:
Ruby, One More Song, Let Your Wall Fall Down

Cheryl Cole:
Rain On Me, Stand Up

Diana Vickers:
Four Leaf Clover, Jumping Into Rivers

JLS:
Crazy For You, Tightrope, Close To you, Kickstart

Katy Perry:
Your So Gay, Fingerprints, One of The Boys

Pixie Lott:
Jack, Band Aid

Rihanna:
Good Girls Go Bad, Breaking Dishes

Sugababes:
Side Chick, My Love Is Pink, Suprise, Thank You For The Heartbreak, Crash N Burn, Sweet & Amazing, Little Miss Perfect

Taylor Swift:
Hey Stephen, You're Not Sorry, Our Song