The Clamshell iBooks have a maximum resolution of 800x600. This can get kind of tiring, trying to fit everything in such a small space. To this end, I wanted to decrease the size of the font of the desktop icons (not just the size of the icons themselves). However, the View Options panel (View: Show View Options, or just command-J) only allows you to decrease the font down to 10 point. This is more than small enough on my iMac or my G5 at work, but on the iBook ... I wanted it a little smaller.
So I searched for the preference file that was modified whenever I changed display settings. Low and behold: com.apple.finder.plist. It (like most plist files) is stored in your user's Library/Preferences directory. These plist files are just plain text, so you can edit them using TextEdit, or BBEdit, or SubEthaEdit, or any text editor. IN the section that begings with this:
<key>DesktopViewOptions</key>
<dict>
Find this property:
<key>FontSize</key>
<integer>10</integer>
Now just edit the integer to whatever size you want (9 was small enough for me; 8 was getting hard to read). Save the file, re-launch the Finder (Option-click and hold on its icon in the Dock), and it's done!
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050304142701329