Default FBReader icon set is ugly as fsck, so I created a 'Candy Icon Theme' for it and now it looks quite nice.
To install it, unpack it as: /usr/local/share/pixmaps/FBReader/ (FreeBSD)
It can also be: /usr/share/pixmaps/FBReader/ (Linux)
If You will not be able to find it, try that way (may take several minutes):
% find / -name advancedSearchOnNetwork.png 2> /dev/null | sed s/advancedSearchOnNetwork.png//g