Here is what I cart around to work, conferences, and travel.

Headphones

Bose QC15 Noise Canceling Headphones

The QC15's are the best active noise canceling headphones I have found.  They are great on airplanes or at a noisy office.  They work so well, I even where them when I'm sleeping on a plane without playing anything through them.

Bose MIE2i Headset

The MIE2i's are a pretty good value.  They sound pretty good, are really comfortable and don't fall out.

iPhone Accessories

Apple Lighting Cables x 4

You can never have enough lightning cables if you are an iOS Developer.

Apple Lighting to HDMI

Great for presenting or playing Netflix on a hotel TV.

Apple Lighting to VGA

For when you have to present at a large company.

Apple 12w AC Charger

Apple 5w AC Charger x 2

Apple USB to Ethernet

mophie Juice Pack Powerstation Mini

Because iPhone batteries.

Storage

This Is Ground Cord Tacos (eBay Branded)

These are game changers.  A co-worker ordered them for swag and I was hooked.

Topo Designs Dopp Kit

All of the above goes in this bag. It is a great size that fits nicely into a backpack, messenger bag or carry on.