http://www.intel.com/technology/iapc/acpi/index.htm (Advanced Configuration & Power Interface)
http://www.lesswatts.org/projects/acpi/ (the ACPI4Linux project at Sourceforge)
http://www.poupinou.org/acpi/ (DSDT patches by Bruno Ducrot)
http://en.opensuse.org/S2ram—How to get Suspend to RAM working
http://www.opensuse.org/Pm-utils—How to modify the general suspend framework