Here you will find different online projects, specifically thought for this medium.

Concha Jerez & José Iges at the Real Academia de España en Roma.
Sound Art in Rome, 1993. 

David Beltran's virtual exhibition

Digitization of Raquel Manchado's archive

Virtual exhibition at

Sound Art virtual exhibition, curated by José Iges

Project by Jesús Ubera Biedma, curated by Ramón Mateos

Freijo Gallery's 10th Anniversary virtual exhibition