Mine (in no particular order) include:

Joe Cocker & Jennifer Warnes - "Up Where We Belong"
Paul McCartney & Stevie Wonder - "Ebony and Ivory"
Linda Ronstadt & James Ingram - "Somewhere Out There"
Barbara Mandrell & Lee Greenwood - "To Me"
Kenny Rogers & Dolly Parton - "Islands in the Stream"
Cher & Peter Cetera - "After All"
Bryan Adams, Rod Stewart & Sting - "All for Love"
Mariah Carey & Boyz II Men - "One Sweet Day"
Celine Dion & Peabo Bryson - "Beauty and the Beast"
Kenny G & Louis Armstrong - "What a Wonderful World"
Whitney Houston & Cece Winans - "Count on Me"
Donna Lewis & Richard Marx - "At the Beginning"
Linda Ronstadt & Aaron Neville - "Don't Know Much"
Linda Ronstadt & Aaron Neville - "All My Life"
Buck Owens & Ringo Starr - "Act Naturally"
Kenny Rogers & Kim Carnes - "Don't Fall in Love with a Dreamer"
Kenny Rogers & Sheena Easton - "We've Got Tonight"
Trisha Yearwood & Garth Brooks - "In Another's Eyes"
Whitney Houston & Mariah Carey - "When You Believe"
Elton John & LeAnn Rimes - "Written in the Stars"

You Don't Bring Me Flowers - Barbra Streisand and Neil Diamond

The Trolley Song - Mel Torme and Judy Garland

(I'm Gonna Get You On A) Slow Boat To China - Bette Midler and Barry Manilow

Sisters - Bette Midler and Linda Rondstadt

What Now My Love - Frank Sinatra and Aretha Franklin

Freddie Mercury & Montserrat Caballe - Barcelona

Ann Wilson & Mike Reno - Almost Paradise

Phil Collins & Marilyn Martin - Separate Lives

Cher & Peter Cetera - After All

Amy Grant & Peter Cetera - Next Time I Fall

Ozzy Osbourne & Lita Ford - Close My Eyes Forever

Barbra Streisand & Neil Diamond - You Don't Bring Me Flowers

Barbra & Barry Gibb - Guilty

Barbra & Barry - What Kind of Fool

Barbra & Bryan Adams - I Finally Found Someone

Barbra & Donna Summer - No More Tears(Enough is Enough)

Some favourite songs in alphabetical order:
Don't Know Much - Linda Ronstadt & Aaron Neville
(Everything I Do) I Do It For You - Bryan Adams & Céline Dion
I Got You Babe - Sonny & Cher
If I Can Dream - Céline Dion & Elvis Presley
Mrs. Robinson - Simon & Garfunkel
Sound Of Silence - Simon & Garfunkel

[QUOTE=Zebra 3]Some favourite songs in alphabetical order:
[I]
[I](Everything I Do) I Do It For You - Bryan Adams & Céline Dion

[I]If I Can Dream - Céline Dion & Elvis Presley
[I]

I've never heard those two. Where did you find them?? When were they
recorded?

Nancy Sinatra and Lee Hazlewood and their songs "Jackson"(Yes,I know Johnny Cash and June Carter Cash did it first),"Summer Wine","Ladybird",and the very weird "Some Velvet Morning" ;

In no partcular order:

Yah Mo B There - James Ingram & Michael McDonald

My Mistake (Was to Love You) - Diana Ross & Marvin Gaye

You Are My Heaven - Roberta Flack & Donny Hathaway

Time To Say Goodbye - Sarah Brightman & Andrea Bocelli

Islands in the Stream - Kenny Rogers & Dolly Parton

First Time on a Ferris Wheel - Smokey Robinson & Syreeta

With You I'm Born Again - Billy Preston & Syreeta

Stay With Love - Jermaine Jackson & Syreeta

Separate Lives - Phil Collins & Marilyn Martin

Solid - Ashford & Simpson

Can't We Try - Dan Hill & Vonda Shepard

Another World - Crystal Gayle & Gary Morris

All My Life - Linda Ronstadt & Aaron Neville

No More Tears (Enough Is Enough) (long version) - Barbra Streisand & Donna Summer

Jackson - Johnny Cash & June Carter

Almost Paradise - Ann Wilson & Mike Reno

Don't Fall in Love With a Dreamer - Kenny Rogers & Kim Carnes

Michael Mcdonald & Pattie labelle- On my own
Brad Paisley & Alison Krauss- Whisky Lullaby
Reba & Kelly Clarkson- Because of you
Bill Medley & Jennifer Warnes- (I've Had) the Time of My Life
Crystal Gayle & Eddie Rabbit- Just you and I
Donna Lewis & Richard Marx - At the Beginning
Cher & Peter Cetera - After All
Reba & Linda Davis- Does he love you
Tim & Faith - Let's make love
Feddie Murcury & David Bowie - Under pressure
Sting & Sheryl Crow- Always on your side
Bryan Adams & Tina Turner- It's only love

1. Feels Like Heaven- Peter Cetera and Chaka Khan
2. Take Me With U- Prince and Apollonia
3. Can't We Try- Dan Hill and Vonda Shepard
4. Sperate Lives- Phil Collins and Marilyn Martin
5. Emotion- Samantha Sang with the Bee Gees
6. Blame It On Love- Smokey Robinson and Barbara Mitchell
7. Don't Give Up- Peter Gabriel and Kate Bush
8. U Got the Look- Prince and Sheena Easton
9. The Next Time I Fall- Peter Cetera and Amy Grant
10. Easy Lover- Phil Coillins and Phillip Bailey

I've never heard those two. Where did you find them?? When were they
recorded?The Bryan Adams duet was performed live a few times before Céline Dion left the music scene in 1999 to start a family and I don't believe it's available on any album.

The Elvis Presley duet was recorded and performed this year on American Idol's charity special Idol Gives Back (http://www.americanidol.com/idolgivesback/). It's probably available on iTunes.

Here's the two duets on YouTube:
(Everything I Do) I Do It For You - Bryan Adams & Céline Dion (http://www.youtube.com/watch?v=ZZqi1TwbhiA)
If I Can Dream - Céline Dion & Elvis Presley (http://www.youtube.com/watch?v=agZTP7I0994)

Adrian Belew and David Bowie: "Pretty Pink Rose"
Eric Clapton and Bob Dylan: "Sign Language"

"Ain't No Mountain High Enough" Marvin Gaye and Tammi Terrell

Any duet by Roberta Flack and Donny Hathaway.