Keyloggers are powerful tools that can perform many task. Standard security measures for machine-to-machine interfaces do not protect computer systems from keylogger attacks. Human-to-machine interfaces must be considered to combat keylogger intrusions. The judicious use of keyloggers by employers and computer owners could, in some situations, improve security, privacy, and efficiency. But the possible positive effects must be balanced against the possible negative effects on employees, users, and children.