Portable Apps, Carry your Apps with you without having to install them!

"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 flash 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."

http://www.portableapps.com/ The place to start finding all sorts of portable apps
WinAudit - " PC audit and inventory of software, licenses, security configuration, hardware, network settings..."
Angry IP Scanner - "Angry IP scanner is a very fast IP scanner and port scanner"
http://www.sysinternals.com - Computer Diagnostic Tools