Just wondering what other bits and pieces most people lug around with their laptop/notebook/netbooks when on the road

I'm assuming many/most carry:
Charger
Mouse
USB flash drive
3G adapter


What about things like:
VGA cable
Ethernet cable
USB-to-serial cable
Spare battery (laptop)
Spare Battries (mouse)
Travel plug adapter.


Why i'm asking is i'm looking at making a padded hard case and i want to know how much other guff most people carry round with them, so i can make sure there is room for all the common stuff i might discover i need later.

Since the moulds will represent a decent investment of time and money, I want to bang out a handful of these and sell them off to recover some costs.  So who is keen on a carbon fibre hard case for their netbook and accessories? If their is enough interest i'll look at doing one suitable for 14" laptops later on.