I liked the idea of having my Ubuntu machine startup in time for my arrival at the office. Here's how it's done:
1) Enable your RTC in the BIOS, setting your desired wake-up time
2) Use the rtcwake command to tell the machine when to wake up. Two variants of this:
sudo rtcwake -s 54000 -m disk
will wake the PC in 15 hours, after immediately doing a hibernate, or
sudo rtcwake -s 54000 -m no
will do a wake in 15 hours but nothing more. I like this latter way since I can then also schedule a shutdown using a package such as qshutdown
I did toy with nvram-wakeup, which is useful for setting the RTC while you're running Ubuntu.
More here http://askubuntu.com/questions/61708/automatically-sleep-and-wake-up-at-specific-times
And if you get the Grub menu after resuming, the fix is here.
