The University of Wisconsin-Madison Libraries’ Parallel Presspublishes "print-on-demand books that parallel online publications, as well as chapbooks featuring the work of regional poets and UW historians." Many of the books are reprints of out-of-print works. It appears that the Parallel Press was established in 1998....
While the chapbooks are only available in low-cost print editions, the books have a freely available digital version. Examples of books include (links are to the digital versions):
The open access movement:
Putting peer-reviewed scientific and scholarly literature
on the internet. Making it available free of charge and
free of most copyright and licensing restrictions.
Removing the barriers to serious research.
I recommend the OA tracking project (OATP) as the best way to stay on top of new OA developments. You can read the OATP feed on a blog-like web page or subscribe to it by RSS, email, or Twitter. You can also help build the feed by tagging new developments you encounter.