On-Screen Keyboard Portable makes it easy to access Windows' built-in on-screen keyboard on any system you come across. It remembers your settings for sound, hover to select or click to select, always on top, keyboard layout and more as you move from PC to PC. And the icon sits right in your PortableApps.com Menu for easy access.
Keylogger Note: While on-screen keyboards offer protection against hardware keyloggers, they do not offer protection against software keyloggers (which are far more common). They are primarily intended as an accessibility tool or for alternate means of text entry (pen-based computing, etc).