Made sticky the suggestion box post, the most consolidated/oldest one (that has the 1st post updated) and a youtube channel post with WWDC sessions, that includes some 2000 and 2001 interesting ones.
I found interesting some Chris Spinoza videos about AppleScript from 2000 and 2001. He talks mostly about Mac OS X, but also about the performance on OS9.
But the Carbon sessions from the iPhone/AppleMaps guy are interesting too to define what is a classic App, how it runs on OSX, what it is a Carbon app running on OS9&X and what is Cocoa.