^I wouldn't regard Front 242 as synth pop though!
Since I'm norwegian, I should of course mention A-Ha. Take on Me from their album "Hunting High and Low", while not as good as the title track, might just be the definitive synth pop song for me.
I also think Tears for Fears deserves mention here

I don't listen to a lot of synth pop, but I like quite a few of their songs. Of couse I remember them from when I was a kid.
And then, just to squeeze in a curiosity, here's Klaus Nomi :
He's not in his traditional get-up here, but the song is so brilliant