Just cruising through

things wife needs and now is in every vehicle

nail clippers
sanding block/file for nails (a broken nail pisses her off because it can snag on clothes etc)
bottle of ibuprofen
Kleenex
pen's and note pad (they have favorite pens so see what she likes to use)
new bottle of her favorite water flavor additive....note NEW not opened yet, otherwise it will be your fault it spilled
favorite lip cream/balm flavor etc

this is stuff added to her bag also

good luck

Sorry to hijack ladies

I know this is an old thread but I thought of a few things that men might forget.

Hair ties
Head band
Tampon/pads
Small case for jewellery or valuables.
I'm sure you have socks already but comfortable shoes is a must
Blister band aids and new skin in case of blisters.
Eye drops
Hand sanitizer