Although not micro, "Legado de Yuste" is pretty good as far as Spanish beer goes and has a great history. It's the closest to a "trappist beer" that Spain has to offer.
Some of the speciality Estrella Damm products aren't too bad either. (Voll Damm doppio malto, A.K. Damm, their new Weiss beer is incredibly close to a proper Munich hefeweizen, and even their bock is acceptable, too.)
Adam