For several months, I've been listening to a custom station on Pandora.  I use OpenPandora too, except I've downloaded the code for OpenPandora and made some changes.  Maybe one day I'll email the project owner and see about getting my changes merged in.

But anyway... for years I listened to CDs that I had ripped.  But my collection grew old.  Then I tried listening to WEBN online, but the commercials were absurd and annoying.

Pandora is simply amazing.  If you've never tried it, give it a 2-5 day trial and you'll probably never listen to anything else from your PC.

By the way, it's Free/Open Source.