http://virtualbiologylab.org/ (currently may require Java, but they seem to be working to update)
https://www.esa.org/ldc/digital-library/
http://annex.exploratorium.edu/imaging_station/ (microscope images)
https://openlab.citytech.cuny.edu/bio-oer/
https://librivox.org/search?primary_key=0&search_category=genre&search_page=1&search_form=get_results (audiobooks)
http://www.perseus.tufts.edu/hopper/collections (ancient classics)
https://www.hathitrust.org/
https://www.gutenberg.org/
https://owl.purdue.edu/owl/purdue_owl.html
https://apastyle.apa.org/style-grammar-guidelines
https://style.mla.org/mla-format/
https://www.chicagomanualofstyle.org/tools_citationguide.html
https://www.openintro.org/
https://edtechbooks.org/
https://openstax.org/
https://open.umn.edu/opentextbooks
https://open.bccampus.ca/browse-our-collection/find-open-textbooks/
http://textbooks.opensuny.org/
https://lyryx.com/subjects/how-it-works/open-textbooks/ (math/stats, business, and economics)
https://www.saylor.org/books/ (textbooks and courses)
https://openoregon.pressbooks.pub/
https://www.oercommons.org/hubs/open-textbooks
https://libretexts.org/index.html (textbooks and courses)
https://www.nap.edu/ (has videos, includes A&P/nursing)
https://ocw.mit.edu/courses/online-textbooks/ (includes some for math and one for Chinese)
https://www.livescience.com/infographics (science related infographics, NOT OER, including a series of ones on the human body from 2013)
https://www.livescience.com/26825-human-body-system-respiration-infographic.html
https://www.livescience.com/27585-human-body-system-circulation-infographic.html
https://www.livescience.com/39024-human-body-system-musculature-infographic.html
https://www.livescience.com/38679-human-body-system-endocrine-infographic.html
https://www.livescience.com/38677-human-body-system-urination-infographic.html
https://www.livescience.com/26824-the-human-body-s-skeletal-system-infographic.html
https://www.livescience.com/26848-human-body-system-digestion-infographic.html
https://www.livescience.com/27975-human-body-system-the-nervous-system-infographic.html
https://www.livescience.com/27990-human-body-systems-the-integumentary-system-infographic.html
https://www.livescience.com/38028-how-the-human-body-s-immune-system-works-infographic.html
https://www.livescience.com/38545-how-the-lymphatic-system-works-infographic.html/
https://www.britannica.com/browse/Anatomy-Physiology (not strictly OER, and an encyclopedia isn't ideal, but they do have nice diagrams)
https://www.ncbi.nlm.nih.gov/books/
https://www.ncbi.nlm.nih.gov/pmc/
https://open.umich.edu/find/find-open-educational-resources (has videos!)
https://amser.org/index.php?P=BrowseResources&FieldId=68 (contrary to name is not just for math and science, though it is heaviest on those areas)
https://oertx.highered.texas.gov/ (largely textbooks and handbooks, many come from other sources on this list)
https://oasis.geneseo.edu/(textbooks, interactive simulations, OA books, courses and course materials, videos, podcasts, audiobooks, public domain books)
https://www.oercommons.org/curated-collections (mostly K-12, but has CTE and Adult Ed resources that could be of value)
https://oer.galileo.usg.edu/communities.html
https://mason.deepwebaccess.com/mason__MasonLibrariesOpenEducationResources_5f4/desktop/en/search.html (essentially an OER database; accesses 21 resources)
https://www.merlot.org/merlot/index.htm (includes video and interactive tutorial resources, including in sciences)
https://digital.library.pitt.edu/collection/university-pittsburgh-press-digital-editions (Out-of-print monographs published by the University of Pittsburgh Press between 1938 and 2004)
https://teachingcommons.us/ (includes some K-12 materials)
https://www.elibrary.imf.org/ (data and publications about countries around the world, free but some data requires account)
https://nobaproject.com/ (requires account, but free)