The Encyclopedia of Genealogy or "eogen" is a free-content encyclopedia that seeks to provide "reference information about everything in genealogy except people." One can subscribe to a weekly newsletter that lists the edits.
Quoting from the FAQ:
Can I copy-and-paste the information found in the Encyclopedia of Genealogy and use it elsewhere?
Yes! Because the information contained here is contributed by many people, the Encyclopedia of Genealogy makes no copyright claims. The information contained herein belongs to all genealogists, not to the Encyclopedia of Genealogy. However, we do suggest that you give a brief reference as to where you found the information, such as a source citation of: "Encyclopedia of Genealogy, http://www.eogen.com" or for a specific term such as GEDCOM, "Encyclopedia of Genealogy, http://www.eogen.com/gedcom." However, that is only a suggestion, not a requirement.