My commando gear
Apple MacBook
I love Apple's hardware for it's stability and it's resilience. I love OS X because while it has a beautiful and very usable GUI, it takes only one button to reach into its foundations (Terminal.app is on F2 for me), where I can summon the full power of unix to get things done effectively.
Spare: an ASUS notebook with Ubuntu.
25MB Internet connection
My main pipe.
Spare: 4MB Internet connection from different provider, and iPhone 3G tethering.
In the rare times when there's a problem with my connection, I either just use the 3G network, or the connection of a friend's coffee house one corner away from my home office.
iPhone
Surprisingly, the iPhone is much closer to a notebook than to a phone. Not only I have full web access from everywhere, I can also read and reply email. There are tools for monitoring servers and even for SSH-ing into them to start or check on jobs and scripts.
Spare: A Sony-Ericsson Android phone.
Paper notebook
Often the right thing to do in solving a problem is to put a little distance between it and us. Having a bird's eye view of the bigger picture usually offers solutions that were invisible earlier.
At times like this it's good to go to a park or a teahouse armed only with some papers and a pen, and let the mind do what it does best. Scribbling. Brainstorming. Drawing mock-ups. Sketching. Spilling the subconscious onto a paper. Then going back to the computer, and writing it.
Spare: Note-taking and mind-mapping applications on the iPhone. :)