This Yahoo! client for Linux operating system supports almost all of the features you would expect to find on the official Windows Yahoo! client: Voice chat, webcams, faders, ‘nicknames’, audibles, avatars, display images, and more. Yet, it remains very light-weight and memory-friendly. GyachE Improved uses Gtk-2 for its user interfaces (Gtk-2 2.0.6 or better required).
More infos at http://gyachi.sourceforge.net/screenshots.shtml