Chord Chucker's posts do point out some real uses for the circle idea, unlike pretty much everything else in this thread.

Here's another one - not an actual circle, but topologically it's the same, and unlike "Sweet Georgia Brown", it's not something that fits a ladder.

Animated analysis of Giant Steps

Very clever. It does show you what's going on. But how many of us here actually need to understand that for the music we deal with?