On-Screen Ruler - lightweight, free, semi-transparent ruler
CryptoTE - CryptoTE is a text editor with integrated strong cryptography.
Bluegrams Screen Ruler - A lightweight and configurable ruler tool for Windows Desktop.
Notebook PEA - Protects your private notes with a password.
Pixus - Pixus is an AIR pixel ruler application, a handy tool for web and interface designers.
Paranoia Text Encryption - Paranoia Text Encryption encrypts text according to a choice of strong algorithms.