If you use the Google Notebook extension for Firefox, you may notice it takes up a lot more space than necessary. I have a number of other extensions that place icons in the status bar so wasting space with useless text bugs me. It would be nice if Google included an option to hide the text and only show the icon, but that seems unlikely. Luckily it is not hard to remove the text yourself by adding this rule to your userChrome.css file:
display: none !important;
See the Mozilla wiki for more info on userChrome if you need help.