I've got a large fanny pack in the trunk of my car with roughly this in it:
*1 large Nalgene bottle
*1 wool cap, which I think is indispensable for an overnight stay. You lose 80% of your body heat through your head, don't you?
*A couple powerbars or the like
*A bic lighter
*Waterproof matches, just in case the lighter dies
*several cotton balls (with PJ)
*Yes, a small folding knife (but I always have a swak and a small fixed on me)
*15' of paracord, for lashings, shoestrings, etc. I can even weave a fishnet with the inner pieces.
*Fishing line and a couple hooks. again, just in case.
*Pencil and some paper
*Some water treatment tabs. Katadyn micropur is what I have.
*Emergency blanket.
*Emergency poncho.
*9 hr candle
*Fox 40 whistle
*I have a pocket chain saw...you could leave that out.
*4 of the big hand/boot warmers from Walmart hunting section. I agree, these would do great in either a tube tent or inside your coat.
*Little bit of TP. Oh, the comforts of home.
*Small LED flashlight and...
*two 12-hr lightsticks. Overkill? The flashlight is for reading and the lightsticks are for the rest.
* About $2 in quarter plus a larger bill
* 1 needle and a good length of thread
* A small Purell, but in my kids' packs I've put in a small pack of anti-bacterial wipes.
*Lowes sells a roll of trailmarker tape that alternates between blaze orange and reflective gray. Works in the day and night!
*Here's a short online manual you can print:
http://www.gerbergear.com/docs/GLB_Cold_Weather_Survival_2005.pdf
* Here's another, for desert:
http://www.maricopa.gov/emerg_mgt/pdf/survival.pdf
*I also have a metal cup
* a chapstick
* I might add a portable cell phone battery charge.
Yes, it has some weight to it, but I got it all in the pack and feel much better about it.