You see, as a writer-type I have a lot of stuff that I've written over the years. It's my habit to write something, print it, and read it. I keep printed copies specifically so I can reread things at my leisure; the problem is finding the printouts and keeping them organized. Frequently I end up with multiple copies floating around, or new versions, or what-have-you; and there is no good way for me to store any of it.
Kindle DX would solve that: dump the word processor files to PDF and put copies on the Kindle. With its native PDF support and 8 GB of on-board storage I wouldn't even need to put in an SD card to hold my entire ouerve. (Even if I were to somehow get all the C-64 stuff in here. I'm still not entirely sure how to do that, though.) The PDF archives of the Fungus, whatever D&D books I've got PDFs of, whatever manga I've got--all of it. A library I could carry with me wherever I went.
Of course, I could also buy e-books and make heavy use of various Internet archives of works that have entered the public domain. There is a lot of e-text out there.
The price for the thing is still steep, but that 9" screen is the deal-maker for me. The screens of the smaller units are impressive in and of themselves, but I didn't see how they would work for viewing my own work. E-paper is cool stuff, and there really is no practical reason they can't make them arbitrarily large, save one: refresh time.
The biggest liability of e-paper is its refresh rate. It takes about half a second to change pages--not because the computer hardware is slow, but because e-paper just changes states so slowly. And the larger the screen is, the longer it takes to change all the pixels, because there are more of them. (Make a screen 2x wider and higher and you've got 4x the pixels.)
But once you set e-paper into a state, it remains in that state until you change it. That's why these things have such long battery life: no backlight and a display that only draws power when it's being updated. (I think a proper ebook should have a small solar cell in it to trickle-charge the battery. You can't read without light anyway.)
So I may be embarking on another quest to save money for another techno-toy. I don't know; I want to upgrade the desktop's video card, which is sure to cost a packet, too. So I guess we'll see how things go.