Are you a happy user of the numpad on your keyboard? With ControlPad Portable you can execute lots of commands using three digit numbers, and use it from your pen drive.
Once executed, a little icon is added to the system tray. To execute a number shortcut, hold the '*' key for 150 milliseconds (this is definable), then tap in the launch code and hit return. There is an options interface, although its language is very much aimed at the advanced user. If you're up to speed with tech jargon, it's not so bad!
You can set commands by tapping a code, hitting the Numpad '/' key, which then lets you choose an .EXE file to run. You can also set up codes by altering the the command file. This is simply a text file, and you have to manually add commands. The format is simple, luckily, so, for example Firefox might be 11=C:\Program Files\Mozilla Firefox\firefox.exe.
When the activated, as you type your number, a green light appears if a correct command has been entered. It's possible to turn that window off, so ControlPad operates totally invisibly, though it doesn't affect the high speed of the application. This portable version is useful, but obviously some commands may not work on computers with different file paths.
People who use the numpad will find ControlPad really easy to get into, as long as they can remember lots of numbers!