Portable app

I started a new job last week, I am contracting for the first time. I needed some applications installed on my desktop at work, but to do so would not be permitted as part of my clients standard build policies. So I started making a USB disk with the tools I needed and in doing do I found the Portable app and The Portable Freeware Collection websites which ease the process no end

A portable app is a computer program that you can carry around with you on a portable device and use on any Windows computer. When your USB thumb drive, portable hard drive, iPod or other portable device is plugged in, you have access to your software and personal data just as you would on your own PC. And when you unplug, none of your personal data is left behind.

Update

There is also a portable version of Opera available called OperaUSB