The included dictionary on Kindle 3 is one of the things that I appreciate, but that also frustrates me. I'm becoming spoilt, but using the 5 way controller to highlight the word is becoming a drag. I'm looking forward to the way the Touch models handle it.
I rarely looked up words in my reading before the Kindle as I couldn't be bothered grabbing the nearest dictionary. However, having immediate access has certainly changed that for me. Sometimes, after understanding words only through context over time I am left with an imperfect understanding and my own usage is occasionally "off". It's nice to get a clearer picture.
I don't have a list of words at the moment. My vocabulary is not nearly as rich as some readers here, so I might feel somewhat embarrassed publicising my ignorance.
I'm all for authors artistically re-purposing words though if it helps the story telling. It might be because I used to enjoy writing poetry, but it was occasionally effective to misuse words to create certain sounds or pictures in my head when reading. I expect an author not just to use prose, but to use it to the best possible effect and this can sometimes be achieved with great success through misuse as well as through correct use.