IBM Lotus One UI is a series of design guidelines and code samples to help IBM's developers make more consistent and usable web applications.
Design specifications
HTML and CSS samples
I contributed many articles and markup examples to IBM's one UI project. These guidelines take special care to include accessibility and globalization, since all IBM software must comply with the Americans with Disabilities Act Section 508 Standards. The work was eventually codified into a One UI CSS and HTML library that is currently being adopted across many divisions of IBM.
An excerpt from the One UI guidelines on tagging.An excerpt from the One UI guidelines on date stamps.