I remember getting "Prelude to Foundation" as a gift when I was in middle or high school. The intro to the book contained this list and it was a great way for me (pre-internet) to get a concise listing of the stories in order. Ended up going through the whole list eventually even though I'd read some of them already.
It happened that I read the initial robots, empire and foundation cycles first, and then the "glue" novels that Asimov later wrote for the sake of general consistency. And those added novels contain wonderful twists - it was such a pleasure to read them!
Also, "The end of eternity", it's partially related. In one of the books (I don't remember on what exactly, could be "Foundation and Earth" ? ), he makes a references to what happens on these book.
Was gonna post just that. The "end of eternity" arc is referenced in Foundation's Edge.