This is a re-engineered version of HashColouredTabs by Terry Yuen; It will now also show the coloured icon in the location bar, the ‘List all tabs’ dropdown (Firefox 2), History Sidebar and menu, Bookmarks Sidebar and menu, urlbar autocomplete results, and the back/forward dropdown (Firefox 3).

[When your tab bar becomes full of tabs, you often have to rely on seeing the website icons to tell which website is loaded inside which tab. But not all websites have predefined icons. This extension will give each tab an icon that is coloured depending on the web address (web domain) from whence it is loaded. (HashColouredTabs description)]