If you are running the new eclipse platform which is 4.2 on linux you have already seen that the fonts sizes of view titles are pretty big. To adjust the font size for your prefference you need to edit the following file e4_default_gtk.css which is inside org.eclipse.platform_4.2.1.v201209141800/css. The version number might differ based on the updates you have installed in your sdk. The following entry in the above file needs to be change by providing the font size you would like to have
In above as you can see i have changed the default size to 8. Now save the file and start eclipse. You will have nice view titles which will match to you preference :).