There is Gnome, there is KDE (more configurable), and there is Xfce (lighter). And there is my custom desktop environment based on Fluxbox window manager :-p.
 Window manager : Fluxbox
 
 Taskbar, Traybar : Built in Fluxbox
 
 Keyshortcuts management : Built in Fluxbox, + lineak for multimedia keys
 
 Pager : fbpager
 
 System monitor : Conky
 
 Network manager : gnome-network-manager
 
 Power manager : gnome-power-manager
 
 Clock : stickytime
 
 Screensaver/Lock : gnome-screensaver (with its wonderful “leave a message” feature!)
 
 Graphical sudo : gksu