Better access to non-default dictionaries
I would personally like easier access to dictionaries other than the one I have selected as the default for a given language, preferably from the dictionary window after the Kindle has already looked up a word. It would also be great if, after I've selected the second dictionary, the original term I looked up could be looked up automatically (i.e. without me having to retype it) in the second dictionary.
The current way of accessing these dictionaries is long and complicated: exit the book you're reading, go to the end of the home screen, locate and open the Dictionaries folder, select and open the other dictionary(ies) you want to check and type in the term manually. This is often enough to put me off using other dictionaries while I'm reading.