More than anything, music connects me to a period in my life. I can hear almost any song from my past and link it to an era or an event. Sometimes even to an intersection of road where I first heard that song (I listen to music in the car mostly).
As for my kid, I listened to mostly kids stuff when he was younger (so yes, I can sing along to pretty much any Wiggles tune). But in recent years, I've started introducing him to the music I have always liked, and in pretty much the same order that I became familiar with it. That has allowed me to take a nostalgic journey of my own. And it has been awesome.
We started out with KISS when he was 3 or 4, then to more 80's hair metal like Bon Jovi and Guns n Roses (well not ALL the songs heh), then harder stuff like Metallica, and now we're in the mid nineties alternative stage, where he's getting into the Pixies, Beastie Boys and Jane's Addiction.
Of course, I make sure to only expose him to songs that aren't too explicit...