Alberto Mendes, Manuel Lemos, and Mr. Franks performing Portuguese songs and music from the Azores, 1939
A collection of recordings of Portuguese songs and music made in 1939 by Sidney Robertson Cowell in Richmond, California; includes descriptive notes and audio samples.
Chasing the Fado
An article by an enthusiast for "those Portuguese Blues"; includes discography and resource lists.
Wikipedia article describes the style of Fado which developed in the university town of Coimbra.
From Wikipedia, the history of this Portuguse folk music characterized by mournful tunes and lyrics.
Fado - The People's Soul
The origins of Fado, with photographs, sound samples, and essays on the Portuguese guitar. [bilingual]
World Music Central - article describing the characteristics of Fado.