I agree w/ "Nothing Else Matters" by Metallica, all the Bon Jovi ballads, DMB, and "Everything" by Lifehouse...
but I need to add:
"More Than Words" by Extreme
"Morning Afterglow" by Electarsy
"Can You Hear The Dolphins Cry" by Live (for that "angry" sex mentioned earlier

),
"Deep Inside of You" by Third Eye Blind
ANYTHING by Sade
"Six Underground" by the Sneakerpimps (more of a
before sex song...)
"Wondeful Tonight" by Eric Clapton (more of an
after sex song...)
"Still Loving You" by Scorpion
"When Doves Cry" by Prince