Old Music

I recently had the realization that no matter what I do I will never be able to listen to all of the music in the world. So how can I possibly have a good balance of music, between classic old songs and great new hits that are coming out every day?

So new music I've usually got a handle on I see it when it comes out and I see recommendation on my last.fm account for similar bands with new music, so that's all good.

Then there's music that isn't new but is still from the last five or ten years. That stuff is pretty much in the same category as new music it's easy to find and some of my favorite albums are a few years old, but they still feel pretty new to me.

Really my only issue is old music. It's really hard to discover old bands when they aren't coming out with anything new, so I only really know classic old bands. Recently I've been listening to a lot of Pink Floyd and Tom Petty. But I'm sure there are some great old bands that I'm not going to discover. Solution: there needs to be a music site to promote great old music that isn't very well known. Anybody know about a site like that?