I learned nearly all my CO methods here at KH.
Long Tail CO
Figure 8 (provisional) CO
Crochet (provisional) CO
I learned Judy's Magic CO from Cat (of the "udder needle") Bordhi.
This can be used as a provisional CO or as a alternative method to do a Tubular CO.
(From Crochet I know of a different meaning of "magic loop" that doesn't refer to a loop (or two) in a long corded circular needle.)
Here are two flat, circular COs that use a loop in tail that is drawn tight to "magically" make the center hole disappear.
Circular cast-on two similar ways (video by djinnj
Those would be great for a top down hat, a doily, table cloth, or circular shawl or dish cloth.
I'll be looking for new CO methods, but part of the difficulty is identifying similar methods that merely have different names because of alternative executions.