Thanks for the link...that is an interesting site.
I especially got a kick out of the "Here's your sign" thread. It is funny, if anyone hasn't read it, you should.
I might find it more interesting than some, because we kind of play that game with newbie whitewater paddlers. You'd be surprised at how many times rafting customers ask their guides if they are going to end up where we started. "Yes ma'am, this river is one big circle" is the standard answer. I guess they have been spoiled by Kali River Rapids and the like.