I hear a song and decide I like it so then I have to listen to everything by that artist non-stop for weeks until I get sick of them.
I listened to Dido for a few months, then Lily Allen, City of God soundtrack...
My current favourite is Lenny Kravitz.
It's not that I didn't like him before but I just started re-listening to him and he's just so great.
I got a bunch of his cds from the library and copied them over to my iPhone, and this way I can edit out the crummy ones.
I remember when I was having Alexander and when I was brought into the surgery to get prepped for him to be removed from my body, "Are You Going To Go My Way" was blaring in the room. It was so great, I was so high, and I love that memory.
This way now I think of my son whenever I hear Lenny.