This is a great question, and one to which the answer is ALWAYS changing. Of course there are a few core pieces of equipment that never really changes, but I am constantly updating my equipment and adding more!
Right now, this is what you will find in my bag(s):
Cameras:
Nikon D810
Nikon D700
Lenses:
Nikon 24-70 f/2.8
Nikon 70-200 f/2.8
Nikon 105 Macro
Sigma 35 f/1.4 ART
Speedlights:
3x Nikon SB800s
Flash Triggers:
A bunch of Photix Strato II transmitters & receivers
Tripods, Stands, Light Modifiers:
Manfrotto Tripod, several Manfrotto light stands in different sizes, a Manfrotto Background Stand, several umbrellas & soft boxes, all of which are very portable!
Memory Cards:
More than I can possibly need of the fastest cards SanDisk has to offer, ranging in sizes from 8GB to 64GB
Batteries:
Rechargeable Eneloops for anything that requires AA or AAA batteries, and original Nikon Batteries for the cameras.
Bags:
My two main bags are a Lowepro x200 and the Herritage bag from Shutterbag (it’s so beautiful!). I also have a Shootsac but that doesn’t get too much use anymore.
I think that covers the important stuff. I can’t wait to see what makes it to the list next, I already have a few ideas!