Carrying your laptop with the right stuff installed is not enough.
Not only software, carrying your own hardware and peripherals will save you hours one day:
Here are the things you should also physically carry:
Business cards
A network cable (optional)
An extension cord (optional)
A thumb drive on your keyring (a personal choice, but 16 GB is a good choice)
An external hard drive (a personal choice, but 750 GB if a good choice if you have lots of 10+ GB VMs)
Software DVD's (generally you can keep the .ISOs of MS Office and Visual Studio D:\DataSetup\ISOs)
Current brochures - Hand them out to interested clients
User story cards - These help Product owners create user stories
Evaluation forms - Ask for feedback if you did a presentation
Even a textbook or two
We have one guy in our office who carries two bags, each weighing about 10 kgs. He is the SSW St. Bernard! *
If you need to quickly share something with your mate:
Fun fact: One of our mean guys put a house brick in the bottom a bag to see if he noticed it. He carried it for 2 weeks. It was very funny.