Regulations.gov is a website that hosts U.S. government regulations from over 300 agencies with the following functionality (quoted from the site):
Search for a regulation such as a proposed rule, final rule or Federal Register (FR) notice
Submit a comment on a regulation or on another comment
Submit an application, petition or adjudication document
Sign up for e-mail alerts about a specific regulation
Quickly access regulations that are popular, newly posted or closing soon-directly from the homepage
Subscribe to RSS feeds by agency of newly posted FR notices
Besides supporting the traditional e-rulemaking process, the website has a remarkable design: The site itself looks like a page in a book and tabs have the look of post-its. In addition to the search functionality (search for proposed rules, search for final rules, submit comments, submit and read comments), the page has a few Web 2.0 functions including sharing to over 60 different social networking services and RSS feeds.