There’s an amusing article on The Luminous Landscape about what all you need in your photo bag.
It’s quite funny to see how the author is almost getting religious about all those gizmos and things he needs. Digital is being presented as the ultimate - meaning you also have to lug around a laptop. You can use that laptop to watch movies at a hotel - that’ll also prevent you from getting a dose of the culture of the country you’re in or from just being outside without walking around like some special forces soldier.
PS: I bet that 99.99% of all photographer who end up buying all that stuff will never ever be in a situation where they need it - call that the SUV Effect where the overweight suburban Middle Class, tormented with anxiety because of too much crime on TV, buys cars for which it has zero need.