If you’re looking for a bit more complex (features rich) shutdown/restart/sleep/hibernate scheduler that can be used in Ubuntu, then qshutdown is a really powerful tool that’s worth trying.
But its simple cousin called ‘GTK-ShutdownTimer’ is also pretty good too :D. You’ll need to have “sudo” (administrative) privileges while using it, otherwise you won’t be able to use its functions.
Main features …
*. Schedule Shutdown, Reboot, Sleep Mode and Hibernate.
*. Change timer settings (based on minutes and hours).
*. Shows a countdown on its window.
*. Manually cancel the countdown.
However, while scheduling, unlike with qshutdown, we are only left to use the built in timers rather than entering our own values. So be aware of that.
If interested, you can install “gtk-shutdown” in Ubuntu 12.04 Precise Pangolin, 11.10 Oneiric Ocelot, 11.04 Natty Narwhal, 10.10 and 10.04 by first downloading the “.deb” package from this official gtk-shutdown download page.
Then once the download completes, double click on the “.deb” package and follow the on-screen details to install it. Good luck.