You guys really know your stuff. Even if I don't reply to all of you individually, rest assured I'm reading all your posts with the attention they deserve.
As sun surfer mentioned, there's a lot of new things waiting to come out this month or the next. There's the new Sony readers and it seems Amazon is planning to release its new tablets in October, including a 7" one (same size as the nook color).
I've been hunting after videos on youtube that show dictionary look-ups in action for various e-readers but I didn't keep the links. It did seem that the Sony readers, with their double-tapping on a word to look it up, were the best. Perhaps from now on I'll post what I find here for reference and for others that might be interested to take a look too.
In the meantime...
*drools* ...that's an iPad, so probably too bulky to read comfortably in bed, pretty pricey and of course it's LCD. Nevertheless, and although a picture isn't enough to illustrate the whole process of looking up a word, that would be a dream come true. Not to mention a full-blown tablet has many other uses that an e-book reader doesn't (mainly surfing the web).
If anyone's interested, I've found this link
that describes how an iPad can be best used for reading with an emphasis on the "night mode" (black bg), dictionary look-ups and the use of Kindle and Nook apps on the iPad.
That doesn't mean I've ruled out e-ink based devices yet.
Edit : here
is a video showing the double-tap look-up thing with a Sony PRS-650 *double-drools*