The new Transport&Environment website is probably one of the most exciting websites we've developed in 2011. In early January we've released the beta version and are now working on some advanced features. We've been contracted to host the site and extend it as part of an ongoing contract.
Some of the special features include the option for users to browse the entire site by topic, the comprehensive filtering options available and the campaign pages. Most of the work was custom development although we've used many awesome, pre-built Drupal parts.
Test spin at http://www.transportenvironment.org