I'm late to the dance, my suggestions have already been aired. :P

My big ones would have been:
-Heatsheet (they beat the mylar things like a drum)
-small PSK (PSP or SOL or build your own)
-spare batteries and maybe a head strap for your flashlight
-water
-something to eat
-thermal layer, thin poncho
-map (PSK will have compass that is good enough)
-phone card (they work at the oddest times)
-cash

And wow, you spend how long in commute each day? At that type of time frame, I'd look to arrange to have a place to crash in an emergency, even if it is just a sleeping bag in the office.

If you've got room, a non-contact current detector and a silcock key would be excellent. And if you are worried about creating friction with pepper spray, a small can of WD40 works half way decent and is so innocent that no one will say boo, but it hurts. Or spray deodorant.