Values in about:config that aren't disabled
dom.event.clipboardevents.enabled set to FALSE - Don't allow webpages to mess with the clipboard. dom.disable_window_move_resize set to TRUE - Don't allow webpages to move or resize the browser window. dom.ipc.plugins.flash.subprocess.crashreporter.enabled set to FALSE - Don't report flash plugin crashes.
I know flash is disabled in regards to the 3rd one, but there's no harm in disabling this.