i have nokia x3 which supports books in jar format
I got it all: software to convert files into jar. In book i can control backlight (excellent job i can read in the dark no probs!) font size, background and font colours (250) i've set black background with white fonts better for your eyes,you can bookmark stuff find text you need navigate in the text and i didn't need to install nothing. plus all the books i make with cover so i have my tiny library in the pocket