I would like Amazon to come up with a mechanism for lending e-books -- e.g., my husband & I both have amazon accounts. Right now, we have 1 Kindle. If we got a second one, I see no reason that I should have to pay for duplicates of books he's purchased -- I don't have to pay to read regular books in our house, even if he bought them. I suggest there that there should be some way for him to remove the book from his kindle, put it in the archive & assign it to a different email account (either mine or a friend's) & then for some set period of time, I would have access to the book on my Kindle.
A second feature would be a light wedge to illuminate.
A third feature would be detachable solar chargers with magnets on them so the solar chargers could charge themselves while sitting atop my car during the day, & then I could use them to charge my electronic toys at night (obviously a desire not specific to the Kindle).
A USB connector that is common to other electronic items & not unique to the Kindle.
More textbooks for sale to replace having to lug really heavy books about.
International connectivity -- one reason I want a Kindle is for travel -- I understand that I can get books via my computer, so I don't have to have wireless connectivity, but I also have colleagues overseas who really want a Kindle.
Non-English language books
Text-to-speech in languages other than English
A waterproof case to protect from catastrophic coffee spills at Starbucks...