I bought an eco-reader which permits me to put folders into folders into folders etc.
A have made up folders called A, B, C, D etc. In the folder called S I have another folder called e.g. John Sandford. In his folder I have 3 folders - Prey, Kidd and Flowers - named after the series of books that he writes. Therefore, if I want to read 'Rules of Prey' I go to the folder for S, then to the folder for Sandford and and finally the folder for Prey. Does this make sense? I have almost 2000 books and the eco-reader works for me.
It has a 2 meg internal memory which can be expanded to 4 GB with a SD memory card.
I'm quite pleased with it but I am on the lookout for a new e-reader - as long as it permits me to organize my books in the same way.
http://www.ecoreader.com.au/