On-Screen Ruler - lightweight, free, semi-transparent ruler
GetDeb - GetDeb extends the existing software options for Ubuntu (and derived) Linux distributions by...
Bluegrams Screen Ruler - A lightweight and configurable ruler tool for Windows Desktop.
CNET Download.com - CNET is the premier destination for tech product reviews, news, price comparisons, free software downloads, videos, and podcasts.
Meazure - What are the dimensions of that image? How big is this window?
Softpedia - A library of over 1,000,000 free and free-to-try applications for Windows, Mac, Linux and Smartphones, Games and Drivers plus tech-focused news and reviews