Plone community has coined the tag "plone-site" as the official way for anyone to indicate that a website is powered by Plone CMS.
Plone sites generally have a distinct ‘look and feel’ that you will come to recognize once you see a few Plone sites. Most sites created using Plone will look similar, unless they have been heavily customized. Not all Plone sites have to look like the same, no. Web programmers are able to take Plone sites and customize them heavily so that they look a lot more appealing.
Featured Plone Sites
Here's a brief list of featured sites powered by Plone:
Brazilian Parliament
The Brazilian government is an international leader in open source. Plone powers the main websites for the Brazilian Parliament, the Brazilian President and the Brazilian Government Web Portal.
Central Intelligence Agency
Central Intelligence Agency (CIA) is an independent U.S. government agency that is responsible for ensuring national security. The CIA's responsibilities include collecting, correlating and evaluating intelligence related to the national security and providing appropriate dissemination of such intelligence. CIA provides overall direction and coordination of the collection of national intelligence outside the United States through human sources as well as performs other functions and duties related to intelligence affecting the national security.
Connexions
Connexions is an environment for collaboratively developing, freely sharing, and rapidly publishing scholarly content on the Web. It contains educational materials for everyone — from children to college students to professionals — organized in small modules that are easily connected into larger collections or courses. More than a million people from 157 countries are involved in the creation materials from various areas from computer science and music - to biology and mathematics.
eBay Developers Program
The eBay Developers Program is a program dedicated to helping 3rd parties integrate their businesses with the eBay Platform. As a member of the Developers Program, you can create custom applications that effectively and efficiently handle almost all types of business transactions on eBay (eBay is the World's Online Marketplace®, enabling trade on a local, national and international basis).
Federal Bureau of Investigation
Mission of Federal Bureau of Investigation is to help protect you, your communities, and your businesses from the most dangerous threats facing our nation — from international and domestic terrorists to spies on U.S. soil from cyber villains to corrupt government officials from mobsters to violent gangs from child predators to serial killers.
NASA Science
The Science Mission Directorate (SMD) engages the Nation’s science community, sponsors scientific research, and develops and deploys satellites and probes in collaboration with NASA’s partners around the world to answer fundamental questions requiring the view from and into space. SMD seeks to understand the origins, evolution, and destiny of the universe and to understand the nature of the strange phenomena that shape it.
NetCorps
netCorps is a 501(c)(3) nonprofit organization founded in 1996 to increase the capacity of environmental, social justice and community-based organizations to organize, advocate, and address social and environmental issues through the application of appropriate communication and information technology, training and assistance. netCorps provides technology planning, assistance and support services to hundreds of environmental, social justice and community-based organizations.
Novell OpenCourseWare
OpenCourseWare is a free and open digital publication of high quality educational materials, organized as courses. OpenCourseWare represents a major open access effort and is supported by educational institutions such as MIT, Harvard Law School, Utah State University, as well as Novell, Inc. Novell OpenCourseWare is a collection of educational materials developed by Novell Training Services for authorized courses and other customer training purposes.
Full list of websites powered by Plone, companies-providers of Plone-related services as well as Plone projects developments cases can be found in Plone Network website.