/apps/gnome-session/options
Here you can disable the show_splash_screen option for a login boost. Now go to:
/apps/metacity/general
Enable the reduced_resources option for a significant speed increase. A little further down the tree at:
/apps/nautilus/preferences
You can disable show_desktop to stop Nautilus from controlling the desktop. Of course this means that you won't get icons or a right-click menu on the desktop. Then, travel down to:
/apps/panel/global
Disable enable_animations and highlight_launchers_on_mouseover. Finally, if you append the following line to your ~/.gtkrc-2.0 file (create it if it doesn't exist) you remove GTK menu delays.
gtk-menu-popup-delay = 0