Openbox reboot, halt, shutdown, suspend

Reboot 
dbus-send --system --print-reply --dest="org.freedesktop.Hal" /org/freedesktop/Hal/devices/computer org.freedesktop.Hal.Device.SystemPowerManagement.Reboot 

Shutdown 
dbus-send --system --print-reply --dest="org.freedesktop.Hal" /org/freedesktop/Hal/devices/computer org.freedesktop.Hal.Device.SystemPowerManagement.Shutdown 

Hibernate 
dbus-send --system --print-reply --dest="org.freedesktop.Hal" /org/freedesktop/Hal/devices/computer org.freedesktop.Hal.Device.SystemPowerManagement.Hibernate 

Suspend 
dbus-send --system --print-reply --dest="org.freedesktop.Hal" /org/freedesktop/Hal/devices/computer org.freedesktop.Hal.Device.SystemPowerManagement.Suspend int32:0 

Source: https://wiki.ubuntu.com/DebuggingGNOMEPowerManager