We are using Firefox browser that has been developed by Mozilla. As you may know, Firefox is based on the Mozilla application framework that provides a good way of supporting cross-platform for running applications.
However, supporting cross-platform has some weak points. The first weak point is performance, the second is that it can not utilize the native user interface.
Some web browsers are based on the Mozilla application framework with a native user interface. So they are tightly integrated into the specific platform such as Windows, Mac, and Gnome Desktop to provide their own look and feel. But they are still based on the technology of the Mozilla application framework such as the component model and the 2D layout engine.
These are good examples:- Camino is a web browser for Mac OSX based on Mozilla’s Gecko layout engine using Cocoa framework.
- Galeon is a web browser for GNOME based on Mozilla's Gecko layout engine.
- K-Meleon uses native Windows API to create the user interface (instead of using Mozilla's cross-platform XUL layer), and as a result, is tightly integrated into the look and feel of the Windows desktop.
- Flock is a special web browser that offers some famous web service such as flickr viewer, blog uploader, and RSS Reader.