Audvisor - Sound advice from top experts, all under 3 minutes.
Meazure - What are the dimensions of that image? How big is this window?
microvist - Take on challenges that help the environment
Bluegrams Screen Ruler - A lightweight and configurable ruler tool for Windows Desktop.
Spectrum - Browser-based app to visualize the frequencies of an audio file.
On-Screen Ruler - lightweight, free, semi-transparent ruler