If you accidentally manage to lose (i.e. delete it, like I did!) your applications/login Panel at the top of Ubuntu (v9.10), there's a way to restore it....
Press Alt+F2 to bring up the Command box, then type in gnome-terminal and click the RUN box, this will open the Terminal window.
Then at the command prompt type each line as is and follow each line by pressing the ENTER key thus...
gconftool-2 --shutdown ENTER
rm -rf ~/.gconf/apps/panel ENTER
pkill gnome-panel ENTER
exit ENTER
The Terminal window will close and your Panel will be back in place, albeit without any custom icons you added to it, but you can easily add those again!