I will throw in a response for Sony Reader Daily Edition. It's not perfect by any stretch, but it has some advantages over Kindle:

• It reads pdf, not djvu (yet), as with Kindle.
• It has a feature which automatically zooms to margin, which is very important for latex documents with wide margins.
• It has landscape viewing, like Kindle.
• It has a touch screen, which unfortunately adds a glare to the e-ink because of the plastic laminate sensor over the screen. On the other hand, I find it prohibitively frustrating to try to navigate a pdf document without the touch screen, so it's worth it for me.
• It has a very rudimentary sketch program, about as useful as a post-it note in terms of what you can write on it, due to poor sensor resolution. Still it comes in handy in a pinch.

All in all, it's perfect for reading a paper straight through, probably as good as one can hope for quickly jumping around a document (though more annoying than a computer or actual printout), and convenient for storing many articles. It acts like a thumb drive on other computers, so no need to install any software to load pdfs onto it.