Not enough place on your bookmarks bar ?…
Smart Bookmarks Bar extension comes right here by hiding bookmarks names and only showing icons.

Bookmark names will be displayed on mouse over. This feature can be disactivated if you just want icons without the rollover effect.

This extension is (obviously) compatible with the default Firefox theme.

It is compatible with (almost) all customized themes (difficult to test the 300 which exists !) : Blue Ice, RedShift V2, MidnightFox, Noia 2, iPox, aeroFox, Metal Lion, PinkHope, Aluminium Kai 2, macfox II, Harley Davidson, myFireFox, PitchDark, Red Cats, Mostly Crystal, …

But doesn’t (yet) work with a few : iFox, AzureFox and rubyFox.

1.5 – 2.0.0.*
Version 1.2 — April 1, 2007