Installing Netbeans in Ubuntu may create problem in GUI fonts. Seems system fonts size doesn't affect with netbeans GUI.
We can make font smaller by editing netbeans.conf. In this example, i use netbeans 6.9.1 which located in "/home/ubuntu/netbeans-6.9.1".
So, i edit "/home/ubuntu/netbeans-6.9.1/etc/netbeans.conf" and add this into "netbeans_default_options" :
-J-Dswing.aatext=true -J-Dawt.useSystemAAFontSettings=on --laf javax.swing.plaf.metal.MetalLookAndFeel
Restart your netbeans and you should got font fixed!