I might be anal about things like this, but for some things, I waterproof my waterproof gear <img src="/images/graemlins/smile.gif" alt="" />
If it's that important to keep dry, make as sure as you can that it will stay dry. maybe a nylon stuff sack inside of a ziploc? My BOB is made of Cordura 1000, which as I am told is nearly waterproof. I still make sure the dry stuff will stay dry...unless the pack is dropped into the Amazon and attacked by pirrahnas <img src="/images/graemlins/wink.gif" alt="" />

Simple changes I make to my kits are I take out the bug spray and sunscreen and put in the hand and foot warmers. For cars, I switch to de-icer windshield washer fluid, put the snow brush in and make sure there's some Heet in the kit too. I'm still working on my kits, but those are some simple things I do.