Style Manual
To help you circumvent the common pitfalls that the English language brings along, Andy Taylor created Style Manual, a reference document for punctuation, style, and spelling.
Snazzy Maps - Free Styles for Google Maps
24 ways: Front-end Style Guides
Links to Style Guides
Create a website style guide
Modular Grids
Beautiful UI styling with CSS3 text-shadow, box-shadow, and border-radius - Dev.Opera