Bibliotheka is a site that gathers digital files of books in Spanish. The collections can be searched by title, author, and subject. Files can also be browsed through larger topical categories such as art, science, poetry, or religion.
Individual entries include a brief description of the piece, art cover, file size, genre, and two different options for download. There is also space for users to comment on the piece.
Here’s an example of what you will find for Isabel Allende.
You can take a look at the site here.