Four Leaf Clover - Old 97s w/ Exene Cervenka
For Shame of Doing Wrong - Syd Straw and Evan Dando covering Richard & Linda Thompson
Angel From Montgomery - Bonnie Raitt and John Prine
I’m very fond of Dan Hicks and Rickie Lee Jones dueting on Driftin’. Rickie comes in around the 30 second mark and fully shares the vocals after that.
It’s become an internet meme but I like the song “Somebody That I Used To Know” by Gotye and Kimbra.
Yep. This one is really nice:
Iggy Pop also has a brand new one titled “Dirty Love” with Ke$ha on Ke$ha’s new album Warrior. One reviewer calls it “deliciously, almost uncomfortably filthy.” I defy you to find any other duet that mentions cockroaches doing it in garbage cans, or Santorum doing it in a V-neck sweater.
On the weirder side, there is always Lee Hazlewood and Nancy Sinatra doing Some Velvet Morning.
Then there is always the version by Roland Howard and Lydia Lunch. I’m not sure which is stranger.
David Bowie and Annie Lennox capture lightning in a bottle doing Under Pressure together.
One of Evanescence’s biggest hits (“Bring Me to Life”) had a male part. But maybe that’s still cheesy.
Meat Loaf and Cher - Dead Ringer For Love. I’m not kidding, it’s a pretty decent rocker.
Isaac Hayes & Dionne Warwick once sang a tremendous duet. He would do one line from “By the Time I Get to Phoenix” and she would sing a line from “I Say a Little Prayer for You.” A very moving live performance.
I also like James Taylor and Carly Simon’s version of “Mockingbird”
There is always “The Battle of Evermore” with Sandy Denny singing rings around Robert Plant.
Thom Yorke and Bjork – I’ve Seen It All
Thom Yorke and PJ Harvey – This Mess We’re In
Mark Lanegan and PJ Harvey – Come to Me
Josh Homme and PJ Harvey – Crawl Home
Nick Cave and PJ Harvey – Henry Lee
Are we seeing a pattern yet? 
I love Stevie Nicks, too. How about her duet with Tom Petty, I Will Run to You?
You missed this one.
Not exactly rock, but…
New Dress - Jonatha Brooke and Neil Finn
You Can Close Your Eyes - James Taylor and Joni Mitchell
Two of Us - Aimee Mann & Michael Penn
I’m a fan of Your Love Alone is Not Enough by The Manic Street Preachers with Nina Persson from the Cardigans.
I’m surprised that no one’s mentioned Jackson by Johnny Cash and June Carter.
… Or have I misunderstood the question? :dubious:
Lucky Stars was very popular with the girls when I was in seventh grade back in the 70s.
I’m the OP and still going through the suggestions; I must admit some are very good. Only a few are sappy cheese. 
And I realized I knew a good duet - Obsession by Animotion
Or this one: http://www.youtube.com/watch?v=jsligj1bRFA