Clickable: http://lineofthought.com/

Tools powering Line of Thought: http://lineofthought.com/sites/lineofthought

Here's a few examples pages too:

Tools powering Twitter: http://lineofthought.com/sites/twitter

Sites using Python: http://lineofthought.com/tools/python

Sites using Ruby on Rails: http://lineofthought.com/tools/ruby-on-rails