Occasionally I come across a fact from linear algebra that I have not seen before. These facts are often obscured in search engines by either introductory texts or unrelated papers, and it is difficult to find what I am searching for. It would be convenient if there were some source that listed a large number of such facts, with sketches of proofs for the nontrivial ones. Does anyone know of such a reference of lesser known results in linear algebra?
Note: I found several questions on math.SE looking for an introductory text for self study, but I am looking specifically for a reference useful to someone who is already familiar with the basics of linear algebra, not a book to learn from.