I defy anyone to point out to me where indigo is in the spectrum!

One I learned just a few years ago: Fat Cooks Go Down And Eat ... er ... something-something, which is the circle of fifths (the next one should be B). I Don't Play Loud Music After Dark: Ionian, Dorian, Phrygian, Lorian[?], Myxolydian, [one beginning with A], [another one beginning with D] ... Mnemonics are easy-peasy, but what they mean is another thing altogether!

Steve