Global design firm IDEO redesigned the city of Boston's visual identity a while back. The new (digital only?) seal and website are pretty interesting - as well as some minimal, sans-serif type-based marks. Via the project page:
In the process of the site redesign, IDEO also helped to create a visual identity system that underscores Boston?s strengths: the city?s confidence, humility, personality, and optimism.
In addition to the web architecture and redesign, IDEO also produced a comprehensive style guide to help maintain design consistency, so departments can add content without compromising the overall integrity of the site, as well as a brand look that the city has decided to adopt across nearly all of its consumer-facing media. Now you?ll see the famous underlined B on T-shirts, banners, and even snow shovels.