Galen Framework : Automated testing of look and feel for your responsive websites.
Layout testing seemed always a complex task. Galen Framework offers a simple solution...
YAML Builder : A tool for visual layout development of YAML based CSS layouts
csscss : csscss will parse any CSS files you give it and let you know which rulesets have duplicated declarations.
Sprite Cow : Sprite Cow helps you get the background-position, width and height of sprites within a spritesheet as a nice bit of copyable css.