I think all habrareyd have a constant set of sites that are visited many times a month. Firefox has a convenient bookmark bar for this. But with the number of sites over 20 - it is suitable only if you erase the name of the bookmark, leaving one favicon. It turns out quite comfortable and beautiful.

Even it turns out something like a picture of the day. But all the harmony of the picture spoil the whitening spots of sites without favicon. To resolve this issue there is an extension
Favicon Picker 2 , which allows you to change the icons in the tabs. One more item appears in the bookmark properties:

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In the first picture, the result of the extension is seen on the example of the Runner and Spaylog sites, the creators of which have not yet been honored to make favicon.
Also you probably noticed tabs under the bookmarks bar. They can also be made up of only one favicon-ok. To implement this feature there is an extension
FaviconizeTab . You can configure the event to double-click (or other options) and reduce tabs in size, which is also relevant with active surfing. Finally I want to say:
Citizens! Use unique fav-icons! For this you will be grateful from FireFox users and an extra argument in the fight for bookmark visitors.
PS Maybe you should declare a favicon attribute of Web 2.0 so that everyone can use them? ;)