This is all the hardware (plus cell phone, mine being a prepaid for emergencies only) I carry on a work trip:
Laptop
+ Power brick
+ VGA adapter
+ Presentation remote (with green laser and 4GB drive)
iPod Touch 5
+ Charger cable
+ audiophile earphones
+ sports earphones
Backup hard drive (2TB of space, mostly filled with optional content for work & downtime)
+ USB 3 cable
Large capacity USB flash drives (including a 32GB one on my keychain!)
Rite-in-the-Rain notebook
+ Fisher space pen
Microfleece cleaning tissues doubling as packing material.
Add a magazine to read when electronic devices aren't allowed (I get The Tech and Smithsonian Magazine for free, so I take those and dispose of them when done), clothing (planning helps), toiletries, and food for travel.
The magic enabling the ever shrinking ever more powerful hardware packing comes from multitaskers and digital content.
The iPod Touch replaces a lot of equipment I previously carried (iPod, still camera, video camera, voice recorder, backup remote control for presentation, books to read, and even my iPad 1.0 in many respects). The hard drive carries an hitherto unthinkable library of work and play stuff. (I don't play computer games, other than the occasional solitaire, bejeweled, or mahjong, so I don't carry -- or own -- a game controller.)
The second part of the magic is the move to digital content.
Many years ago I'd carry a small sleeve case with CDs for my Sony Discman (Get off my lawn, kids!!!), some DVDs, paperback books, work books -- hardcover textbooks! -- and other heavy objects with minimal bits-to-atoms ratio. Now I carry thousands of music tracks, hundreds of books, audiobooks, and technical papers, dozens of movies, videos, and television shows, and even a few comic books for nostalgia sake, all as bits on the hard drive. (Obviously these are not the only copies I have of those bits.)
Anything important is backed up in a multiplicity of places: laptop hard drive, portable hard drive, USB flash drives, multiple online services. Because it's well known that anything important of which you only have one copy will, by the laws of Physics, necessarily be lost, inoperative, or confiscated by the TSA.
Of course, you still need to bring a few changes of clothes and toiletries. There's no digitizing those.
