surely tripe, kidneys and tongue, which are similar to meat. Lungs (forbidden in the US) are nutritionally similar to meat, and heart is very lean meat. With brains, liver and spleen you are getting macro doses of certain nutrients and daily consumption might not be advisable in large quantities. If you consider marrow as organ meat, you can certainly eat it daily.
I don´t think that there is any organ meat that is bad per se. Organ meat is generally much more nutritious than muscle meats. If you want to learn more about organ meats, I advise you to watch Denise Minger speech on Ancestral Health Symposium:"Meet your meat". http://www.youtube.com/watch?v=VaEBMoHFrQA
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