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These are the static settings, based on the recommendations from powertop.

# some of these might not apply to your hardware (i.e. different sound chip) or have
# sideeffects (i.e. sleeping sata no longer detecting when discs are exchanged

# powersave for intel hda sound
echo Y > /sys/module/snd_hda_intel/parameters/power_save_controller 
echo 1 > /sys/module/snd_hda_intel/parameters/power_save

# SATA Link Power Management:
for i in /sys/class/scsi_host/host[01234]/link_power_management_policy; do echo min_power >$i; done

# usb devices
for i in /sys/bus/usb/devices/*/power/control; do echo auto >$i; done

# WLAN power management
iwconfig wlan0 power on

# disable nmi watchdog, also possible via kernel option
echo 0 >/proc/sys/kernel/nmi_watchdog

# Disable WakeOnLan
ethtool -s eth0 wol d
ethtool -s em1 wol d

# increase VM Writeback
echo 1500 > /proc/sys/vm/dirty_writeback_centisecs

# Runtime PM for PCI Device Intel Corporation
for i in $(ls -1 /sys/devices/pci0000\:00/*/power/control); do echo auto >$i; done

echo auto >/sys/devices/pci0000:00/0000:00:1c.1/0000:03:00.0/power/control
echo auto >/sys/devices/pci0000:00/0000:00:1c.4/0000:0d:00.0/power/control
echo auto >/sys/devices/pci0000:00/0000:00:1c.4/0000:0d:00.3/power/control

These are the static settings, based on the recommendations from powertop.

# some of these might not apply to your hardware (i.e. different sound chip) or have
# sideeffects (i.e. sleeping sata no longer detecting when discs are exchanged

# powersave for intel hda sound
echo Y > /sys/module/snd_hda_intel/parameters/power_save_controller 
echo 1 > /sys/module/snd_hda_intel/parameters/power_save

# SATA Link Power Management:
for i in /sys/class/scsi_host/host[01234]/link_power_management_policy; do echo min_power >$i; done

# usb devices
for i in /sys/bus/usb/devices/*/power/control; do echo auto >$i; done

# WLAN power management
iwconfig wlan0 power on

# Power Aware CPU scheduler:
echo 1 >/sys/devices/system/cpu/sched_mc_power_savings
echo 1 >/sys/devices/system/cpu/sched_smt_power_savings

# disable nmi watchdog, also possible via kernel option
echo 0 >/proc/sys/kernel/nmi_watchdog

# Disable WakeOnLan
ethtool -s eth0 wol d
ethtool -s em1 wol d

# increase VM Writeback
echo 1500 > /proc/sys/vm/dirty_writeback_centisecs

# Runtime PM for PCI Device Intel Corporation
for i in $(ls -1 /sys/devices/pci0000\:00/*/power/control); do echo auto >$i; done

echo auto >/sys/devices/pci0000:00/0000:00:1c.1/0000:03:00.0/power/control
echo auto >/sys/devices/pci0000:00/0000:00:1c.4/0000:0d:00.0/power/control
echo auto >/sys/devices/pci0000:00/0000:00:1c.4/0000:0d:00.3/power/control

Possibly useful kernel options from http://www.phoronix.com/scan.php?page=article&item=intel_i915_power&num=1 :

• i915.i915_enable_rc6=1 - RC6 was enabled by default for a while, but then it ended up being too buggy for some hardware configuration so it had to be disabled. For affected systems on the current code-base, enabling RC6 can cause GPU hangs. The Intel RC6 feature allows the GPU to enter a lower power state when the GPU is idling.
• i915.i915_enable_fbc=1 - This kernel option enables FBC (frame-buffer compression) for the Intel graphics driver. Frame-buffer compression is not enabled by default since for some systems when frame-buffer compression is active there is a bug where the screen is not being properly repainted when using a compositing window manager. As implied by the name, frame-buffer compression will compress the buffer of what's to be drawn to the screen so that less memory bandwidth is used on screen refreshes, and as a result, less memory being confused.
• i915.lvds_downclock=1 - This kernel option will down-clock the LVDS refresh rate, which can increase power savings as a result. However, for systems that do not properly support LVDS down-clocking, the screen can begin to flicker during use.