If you want to make your gnome-panel’s menu icons a little smaller you can do this, add the line bellow into the gtkrc file of your preferred theme:
gtk-icon-sizes = "panel-menu=16,16:panel=8,8:gtk-button=16,16:gtk-large-toolbar=24,24"
Make it exactly like the line above, of course you can always change some icon sizes here and there, that’s up to you. In case you don’t know where place that line, you can put it straight on the first line. The result will look like this:
In my opinion it feels better with my desktop even though I’ve got a 17″ monitor myself, those huge icons are a waste of screen space. I don’t really need them to be that BIG…
Plus… The screenshot features a nice picture from Italy. I guess I’ve got it from gnome-look.org.