Just to kill time, I recently made a list of all the e-readers I've owned over the years. I used to have quite a collection, but I'm on a purging kick (from watching too many episodes of Hoarders on A&E) and am down to just two.
Here's the list of what I've owned over the years, and photos of the legacy devices. Some of these are PDAs but I did a fair amount of ebook reading on them.
Casio Z-7000 "Zoomer" - PDA 1993
Apple Newton - PDA 1993
Sharp PT-9000 - tablet PC 1995
HP OmniGo 100 - pocket PC 1995
Palm III - PDA 1999
Franklin Ebookman - eReader 2001
Sony PRS-500 - 2006
Cybook Gen 3 - 2007
Sony PRS-505 silver - 2008
Sony PRS-505 red - 2009
* still have, but will probably sell when I get the Sony 350
Kindle 2 - 2009
Sony 600 Touch Edition - 2009
Apple iPad - 2010
Sony 350 Pocket Edition - 2010
*on order in pink