For about two weeks now, I've been listening to the music of this Argentinean band called Los Enanitos Verdes. If you are a fan of rock en Espanol, then, chances are, you'll love the songs of Enanitos Verdes. Check the band's Guitarras Blancas, Lamento Boliviano, and Es Por Ti. My personal favorites now are Eterna Soledad and Una Cancion de Despedida.
And while I'm at it, let me recommend my favorite rock band in the whole wide world: Los Fabulosos Cadillacs. You may want to check their song El Matador, the band's triumphant homage to Victor Jara, the Chilean poet whose hands were amputated by police before thousands of horrified onlookers at a packed soccer stadium after General Pinochet took power. (Victor Jara is generally regarded as the first international star of Nueva Cancion, remembered for his line, "The guitar becomes an instrument of struggle, so that it can also shoot like a gun.") Los Fabulosos Cadillacs has many great songs (they're like the Beatles in their prolific output): the infinitely danceable Gitana, the memorable duet with the Cuban salsa superstar Celia Cruz in Vasos Vacios, Algo Contigo, Mal Bicho, Por Ese Palpitar, Demasiada Presion, Carnaval Toda La Vida... Los Fabulos Cadillacs also has a tribute to Che Guevara--a song named Gallo Rojo-- although I haven't heard it yet. It doesn't matter if you don't understand a single Spanish word; the music is so good it transcends language barriers.