There's a nice write-up on the History of E-Books here
I personally got started with the REB 1100
(320x480 B&W LCD) early 2003, but also had used a "crisp" Sony Clie SJ20
(320x320 monochrome LCD) mid 2003.
I haven't yet ventured out into the eInk reader realm, as they personally don't offer anything I would upgrade for/to. Even though I love gadgets, I prefer functionality over "looks" (I especially avoid iPods). OK, get me a color eInk reader, and then I'll recant the above.
Truth be told, the original Nuvomedia/Softbook readers "did" it right, just with the wrong (closed) business models!