Another consideration is the many different voltages and mains plugs used internationally.
Electricity varies from 110v to 240v, but some power adaptors support multiple voltages. To see if yours does, look for "~100V-240V" on the adaptor.
If in doubt, check with the manufacturer - getting this wrong will be fatal for your electronics.
Adaptors can take up as much space as the gadgets they power. With this in mind, I choose widgets with a micro USB power connector. This means that a single ~100V-240V USB charger plus EU/UK plug adaptors, USB cables (and several USB ports on my MacBook Air) keep everything charged.
2. Noise-Cancelling Headphones
Travelling longhaul means cramped seating and noise. To replicate the experience take a vacuum cleaner. Find the least comfortable chair in your house. Remove the seat's cushions and jam it up against another chair. Sitting on it, plug in and switch on the vacuum cleaner, Try to sleep for eight hours.
Noise-cancelling headphones make a huge difference. They work using small microphones that sample ambient noises (but not the screaming kid in seat 56F). Noise is cancelled using digital signal processing and engine/vacuum cleaner noise is reduced to a dull whisper.
I pack Bose's QuietComfort 20i ear buds. They're tiny but work. I also pack an airline plug adaptor to catch inflight movies.
3. Gaming
When it rains lemons, make lemonade. I use longhaul travel as an opportunity to catch up on gaming. This earns my PlayStation Vita a spot in my luggage. It has a huge library of games and a camera plus a web-browser and WiFi.
4. Reading
Packing paperbacks and magazines would've annihilated my luggage allowance. Instead I pack a Kobo Glo e-reader.
Its backlit display is great when lights are dimmed on board the plane. It holds hundreds of e-books, which can be downloaded free from some public libraries.
5. Computing
From emailing photos to envious workmates to researching eateries, a notebook, tablet, Smartphone/smartwatch is something every traveller should tote with them.
My travel companions consisted of a 13" MacBook Air, Samsung's 8.4" Tablet S, and the soon to launch LG G3 smartphone plus LG's G watch.
Paired wirelessly with the G3 via Bluetooth, the G watch proves instantly useful. Saying, "Okay Google, what is soup dumpling in Chinese?" had it translate English into Chinese so I didn't mistakenly order steamed pig intestines. It also updated to local time as soon as my phone started roaming.
Using WiFi to preload maps on the G3 made getting around easier with no data roaming penalties. The MacBook Air's 10-hour+ battery life was indispensible. Packing Samsung's Tab S means there is always a device available for both of us. Being wafer thin, it uses little space.
6. From A to B
Hiring a car when travelling is enough to induce arguments between even the most polite couples. In the interests of marital harmony, I pack a Navman, my 450LMT GPS, preloaded with maps of our destinations.
7. Say Cheese
I pack two cameras. The 13MP camera on the G3 takes stunning photos and has heaps of different shooting modes. I also pack Sony's WX100 compact point-and-shoot. Its HDR mode cuts out over/under-exposed photos.
8. Road Trips & Kids
There's a special kind of hell parents experience during long road trips in a car loaded with bored children. After the 50th "are we there yet?" whine, car sickness, or all-out sibling squabbles, road trips can be incredibly wearying for parents.
The engineers at Verbatim must be parents, because they've crafted an ingenious solution to road trip hell. Called the Verbatim MediaShare, it's a portable widget that allows parents to hook up to five WiFi-enabled tablets and smartphones, to access data stored on connected SD cards or USB hard drives.
At roughly the size of a deck of playing cards, it isn't terribly big. It is however portable thanks to its built-in battery and can make long trips pass peacefully while restless kids can access movies and music on smartphones and tablets using free iOS and Android apps.
9. Space - the final frontier
So how much space did all this consume? Everything fitted into a small laptop bag which, when taken with regulation sized hand-luggage for my clothes, means I don't check any luggage in - hassle-free travelling!