Ubuntu – How to turn off PCI devices

With the purchase of an Intel SSD and 85WHr Li-ion battery and the linking of wifi and bluetooth to my laptop's wireless switch, extensive Intel PowerTop usage, switching from compiz to metacity, stopping of the desktop-couch daemon, removal of Ubuntu One and several other services from my startup, disabling of everything possible in my BIOS, and physical removal of my optical drive, I've gotten my battery life up fairly high, but I think there's still more to be done. Specifically, when I'm in class taking notes, I want to temporarily but completely power down:

• Ethernet
• Firewire
• USB ports
• SD card reader
• Optical drive
• Webcam
• Sound card
• PCMCIA slot

..without turning them off in my BIOS like they are now, if possible, because then I have to restart my computer to use any of them. As it stands, I still haven't managed to power down:

Firewire
USB connection to webcam
sound card

How do I tell Linux to disable and power down these devices? Is it true that any PCI slot can be physically powered down?

My current idle power consumption is 7.9 watts plus the screen. (10.0W at min. brightness)

Also, how do I set the screen timeout to ten seconds? gconf editor isn't honoring it when I set it to that. Will switching from nVidia to Nouveau save any significant amount of power?