An ultralight fire extinguisher Richard?
Always useful on the Challenge.
On cameras, I am back to minimalist this year.
I have taken an SLR in the past and toyed with the NX10 this year.
I used a proper waterproof camera case, and also a silNylon bag,
attached to the waist strap of the rucksack.
Then a small length of elastic cord and a small carabiner to stop it plummeting down the hill when you take the rucksack off.
Used it recently, but I am going with the Pentax Optio WG1 this time.