A great overview on the history of aspect ratio. I was going to link it to our library, but apparently I have to update the code for the Vimeo videos. Ugh. I'll get to it, just seems my to-do list is a bit like the NTFS $MFT...it only grows, never shrinks! ;)
The Changing Shape of Cinema: The History of Aspect Ratio from FilmmakerIQ.com on Vimeo.