I know I swore allegiance to Spain's Radio Nacional, RNE3, in a previous post, but I've found a great way to mix up both my background music and my Spanish - Radio Tango of Buenos Aires, an Argentinean radio station: La 2x4 FM 92.7

Like RNE3, La 2x4 is easy and free to listen to on the Web. The station plays all tango, all day long, and might be a great choice if you want to tune your ear to Argentinean Spanish, slang and pronunciation.