From Spriteworks Developments:
When it comes to icons, Icon Bank v4.0 is the complete solution. Unlike most collections that use .DLL or .ICL files to store the icons, Icon Bank v4.0 stores them in local .htm files. This is because most of the programs used to compile icon libraries can only save them in 16 colors and so the icons themselves come out looking a little "bleached". The icons in Icon Bank v4.0 are all a brilliant, 256 colors and are ready to use. Icon Bank v4.0 comes with gobs of great features and over 5,000 beautiful Windows icons neatly organized into 54 different categories.