Most modern icon sets are designed for large icons and many colors. One exception is
Monochrome, which, despite its lack of color, is one of my favorite icon sets. Unfortunately, it is for KDE only (and iLiad apps tend to be GTK/Gnome based). In any case, I enclose a set of FBReader icons using Monochrome icons. I did not update the filetype icons.
One way to switch to these icons is to connect the CF card that contains FBReader to a PC and then:
a) On the CF card, goto _local\share\pixmaps\
b) Rename the directory FBReader to (say) FBReader_orig
c) unzip mono-32, and copy directory FBReader into _local\share\pixmaps\ on the CF card
d) Reinstall the CF card on the iLiad
The FBReader directory now contains the Monochrome icons, and so these will be used by FBReader from now on. I have switched FBReader icons many times, and the worse that can happen is that you get the default "missing" icon for any icons that can't be found.
Note that if you update FBReader you should first move FBReader to FBReader_mono and FBReader_orig back to FBReader. That way you won't overwrite the Monochrome icons. This is also how you switch back to the original icons if you prefer them.