Where can one listen to the Occitan language online?

Here's one place, a radio station called Radio Lenga d'Oc. Just click on the play button on the top right where it says En dirècte. A lot of the time it'll just be music though so you might have to wait a while to hear somebody talking.

Apparently it started broadcasting in FM in 1999, and it's based in Montpellier, or should I say Montpelhièr.

From that site you can click on ligans (links) and then media to see other radio stations that might be worth listening to.