Protecting gadgets against rain during touring
The main compartment of most handlebar bags waterproof when closed. Better models have pockets to keep passports dry. There are also plenty of models on the market that have padding for cameras and lenses.

The brand most synonymous with waterproofing is Ortlieb. They make handlebar bags and camera kit inserts for them. There are plenty of other makes on the market, one feature to look out for is the Klickfix bracket that lets you quickly remove the bag for when you are off bike.

As for the computer, the best range of bags can be found in High Street computer shops. For light weight get a neoprene cover with no fancy handles or extra pockets. You can then put your neoprene sleeved computer in a pannier.