Fit a lot more bookmarks onto your Firefox toolbar with Smart Bookmarks Bar. The plug-in takes out the text, leaving just the icon.I have done something similar, where I just delete manually delete the text and just leave the icon. It works great and allows me to keep all my favorite websites just one quick click away.
As a result, you can fit upwards of 50 bookmarks from left to right, versus the 15 or so that'll fit with creative renaming. Of course, some bookmarks are impossible to identify by icon alone, which is why the plug-in displays the text when you mouse over the icon.
Of course some bookmarks don't come with a "favicon.ico" icon. That is where the Favicon Picker extension comes in handy, allowing you to add a new favicon to any bookmark.
And if you don't have a favicon? Use this website to create favicons from any image.