I was thinking about this. It’s very hard, in my opinion, to write a “message song” without coming off as overly preachy or sentimental.
I think Luka, by Suzanne Vega is a decent example of a good song with a strong message that isn’t overly preachy. Joni Mitchell’s “Big Yellow Taxi,” is also a good example of a message song that doesn’t come off smacking of preachiness (is that a word? LOL)
So what are other “message songs” that you think are good without being overly preachy.
Can you give us some parameters for what makes a “message song”?
FWIW, I think “Luka” is kind of manipulative and doesn’t have much of a message, unless “child abuse is bad” counts as a message. And “BYT” seems to be a sort-of-preachy environmentalism song until you get to the last verse, which is about a love lost and lamented–so I’m not sure what the message is, although that’s not necessarily a bad thing.
It seems to me that most songs have some sort of message, whether obvious (“You’ve got to stand for something / Or you’re gonna fall for anything”) or arcane (“And if you listen very hard / the tune will come to you at last / when all are one and one is all / to be a rock and not to roll”) or in-between (“suddenly/I’m not half the man I used to be / there’s a shadow hanging over me / oh yesterday came suddenly”).
splort “Big Yellow Taxi” is the preachiest song I’ve ever heard, and yes I’m including “Give Peace a Chance.”
Oysterband’s All That Way for This - A song of disillusionment with New Labour. (Wait til they see the new lot for a few months!:D)
:Googles “big yellow taxi lyrics”:
:realizes I didn’t know that was the title of that song:
:concurs with voguevixen:
That’s about as subtle as a hand grenade.
I’ve always thought Brick was a very well written song about abortion without being preachy.
I pick Sublime’s ‘‘Wrong Way’’
It’s one of the most depressing songs I’ve ever heard (with incongruously, catchy, upbeat music), and it has a clear moral message, but it’s not preachy.
Lyrics, for those unfamiliar.
YouTube link, for those unfamiliar.
Holy shit, that song is about abortion? I never realized.
I think Concrete Angel is a good example.
I know Cat’s in the Cradle annoys some people, but I think it does a good job of getting it’s message across.
On the other side of that Cat’s Cradle message, In the Living Years says it well.
I’ve always felt It’s Not Easy Being Green had an important something to say.
Teach Your Children Well is a successful example, I think.
“Not preachy” seems to me to mean that a song’s quality is good, standing apart from the message it’s trying to convey.
Off the top of my head:
Imagine
Signs (just too fun and frank to be accused of preachiness)
The Magdalene Laundries- it’s heavy and accusatory, but honest and poetic in its brutality.
And even though it’s literally preaching, I really like Spirit in the Sky.
“Kicks” by Paul Revere and the Raiders is an excellent anti-drug song. And you can dance to it!
“I’m Not Your Steppin’ Stone,” about a social-climbing golddigger, ditto.
I would say, just use your own judgement. No matter what anyone says, someone will disagree, so just chime in with whatever you think is appropriate 
“Amphetamine Annie” tells you in the first line that it’s a message song.
Andy Prieboy’s Tomorrow Wendy, I believe about a friend who died of AIDS.
Paul Kelly’s heartbreaking Christmas song How to Make Gravy a guy in prison sings to his brother.
“Signs”? This is a whoosh, right? That is about the most self-righteously preachy song I’ve ever heard in my life.
I’m with you on “Spirit In The Sky” though.
I dare anyone here to say that Billie Holiday’s “Strange Fruit” is in any way “preachy”.
(Also, “'Big Yellow Taxi” is not about environmentalism - all that stuff is just a metaphor for loss).
Frog Kissin’. Written by Buddy Kalb (Mississippi Squirrel Revival), sung by Chet Atkins, fun, clever, and no preachiness that I can detect.
Great choice but, if I may butt in, the story behind the song is fantastic. I saw this documentary a while ago and was fascinated. A Jewish schoolteacher from the Bronx, surely you’re kidding.