Adding my (short) list:
- Macbook Air 11" - small enough to use in coach if necessary
- Shure e3c noise isolating headphones
- iPhone 4 with international data (and hotspot functionality) - this is a lifesaver
- Priority Pass lounge card. Not a gadget, but a great gift.
Everything else is gravy. Some of the gravy:
- Energizer extended battery for the Macbook Air - I get 10+ hours of battery this way, easily coast to coast uptime working or watching movies.
- Plug adapters for UK, Europe - covers most lounges worldwide
- Kindle touch - for reading in the hotel at night before falling asleep
- Cheap $3 ten-foot extension cord - because those hotel outlets are never where I want them, I like to charge my phone next to the bed.
- Magazine subscription to The Week - I can always grab that week's issue before I go and read half during takeoff, other half during landing and feel somewhat informed of current events