Another one that always gets me is Bob Marley's "Waiting in Vain", in the unrequited catagory. Like many such, the lyrics don't necessarily look like poetry on the page - it's the overall effect with the music and singing which tugs at you.
Hey Dekay (and others), aren't sex songs a different thing than love songs?
P.S. - Hate to be the first jerk to publicly state the obvious (and TEHO & IMO and all that), but more than a few of the nominations above can't help but drive home for me the fact that being into sound doesn't automatically make audiophiles connoisseurs of great music. ;^)