I have traveled for years with two big items: camera gear and books. Not taking books to read or a camera to take pictures is inconceivable for me. My camera gear process began back in 1972 in Japan when I purchased a Canon FTB body and a 50 mm, 24 mm, 135mm lens. I added a tripod, cable release, flash and several adaptor lens. Over the years I switched camera bodies from film to digital, but kept an array of lens and tripod. That was one carry on bag.
Then there were the books. No matter where I travel, I carry several books: a Bible (of course) a novel for relaxation, a non-fiction for growth, and then a Christian Classic or devotional/theological supplement. When we head off to France, our books (Martha is a voracious reader as well) consumes great space and weight!
This year I took the leap and put everything (except my Bible) in digital form, left the camera equipment and stacks of books (goodbye friends!) for the iPad and iPhone. I did take a back-up digital camera I have used twice.
The advantage? I am traveling so light! No shoulder straps and bags of gear! I feel like I blend in more with the population not having an slr camera, but just pulling out the iPhone, shooting and putting it back. And the iPad? All my books, journals, magazines, newspapers and even games (I learned Angry Birds this summer from a little French 6 year old!). I'm not sure I will go back to all the stuff!