On-Screen Ruler - lightweight, free, semi-transparent ruler

SPS Commerce Analytics - SPS Commerce Analytics helps transform messy item and sales data into insights to help meet consumer demand and boost profit.

Bluegrams Screen Ruler - A lightweight and configurable ruler tool for Windows Desktop.

Wiser - Share relevant content w/in your organization.

Pixus - Pixus is an AIR pixel ruler application, a handy tool for web and interface designers.

RQ - RQ by iQmetrix is a cloud-based retail management system for your business that allows you to manage every aspect of your business from inventory, staff, and sales.