This directory of OA journals is hosted by Lund University Libraries in Sweden. From their homepage: http://www.doaj.org:
“DOAJ is an online directory that indexes and provides access to high quality, open access, peer-reviewed journals.” One can search by keywords or browse through broader and narrower subject headings.
These stats are from their website, accessed Sept. 28, 2015:
Seen in “Outstanding Websites of 2014”, Choice, Sept. 2015, p. 33