Clannad’s Last of the Mohican’s “I will find you”
Loreena McKennit (and less so Enya) have some nice ones too…
Madredeus - Portuguese Music.
Brazilian MPB (or new brazilian “Jazz”) has some great stuff. Caetano Veloso in special.
“Slow Ride”; Foghat, on vinyl, at 16 RPM.
Stir It Up by Bob Marley
Crazy Love by Van Morrison
Fields of Gold by Eva Cassidy
Angel by Shaggy (strangely effective, must be the beat)
Slave to Love by Brian Ferry (well the whole Boys and Girls CD)
Well almost anything by Roxy Music, especially Avalon.
Mazzy Star and Sarah McL are good choices as well.
I can’t believe nobody’s mentioned Sade!
Her album Lovers Rock is pretty much just that. It’s like massage oil on CD. I’ve had some seriously good times when that album’s on. 
For a specific track recommendation, try King of Sorrow or By Your Side. Seriously sexy.
A recent make-out fave of mine is John Mayer’s "Your Body Is A Wonderland."
Moving this to Cafe Society.
Paradise By The Dashboard Light by Meatloaf.
Kee-rist…I’m surrounded by heathens.
It’s an acknowledged fact that “When a Man Loves a Woman” by Percy Sledge is the best face-sucking and/or bellyrubbin’ music that ever been wrote.
80s nostalgia ahead, totally for the beats…
In the Air Tonight – Phil Collins
Careless Whisper – Wham
What’s Love Got to do With It – Tina Turner
I’ve Been Waiting for a Girl Like You – Foreigner
You really want to make out to a song with a verse like this:
You Mods are weird!
Group 4 by Massive Attack
That chick from the Cocteau Twins (Liz Fraser?)…her voice is so ethereal.
I Belong To You by Lenny Kravitz
6 Underground by Sneaker Pimps, if you can ignore the words (easily done).
Schooled in the Trade by People Under the Stairs (no words, just groove).
No Ordinary Love by Sade might help you turn it into more than just makin’ out…
“Protection” by Massive Attack is potent. I dare you to not make out while playing this song.
Also, I’ll second the votes for Sarah McLachlan and Roxy Music.
John Phillip Sousa’s “President Garfield’s Inauguration March.”
. . . But maybe that’s just me . . .
All is Full of Love—Bjork
Rachel’s Song—Vangelis (From the Blade Runner soundtrack)
“True” by Spandau Ballet
If you like classic rock, I’ve read that Bob Seger’s album “Night Moves” is ideal for making love to.
I can’t believe the horrible musical taste of posters on this thread. Another depressing example of the state of American music education and the culture we deserve.
Was that tongue-in-cheek, or were you intending to come off as a gigantic elitist snob?
Oh, and:
Sammy Davis Jr. - That Old Black Magic
Oh, and might I suggest…
Girl, You’ll Be A Woman Soon by "Urge Overkill "? You’ll find it on the Pulp Fiction soundtrack.
“Chelsea Bridge” by Ben Webster, on the Ballads album.