Variety of political movements inspired by the work of Henry George:
"Georgism is a philosophy and economic ideology that holds that everyone owns what they create, but that everything found in nature, most importantly land, belongs equally to all of humanity. The Georgist philosophy is usually associated with the idea of a single tax on the value of land. Georgists argue that a tax on land value is efficient, fair andequitable, and will generate sufficient revenue so that other taxes, which are less fair and efficient, can be reduced or eliminated." (http://en.wikipedia.org/wiki/Georgism)
"Georgists tend to believe that all humanity rightfully owns all land in common and that individuals should pay rent to the rest of society for taking sole or exclusive use of that land. People in this movement are often referred to as "single taxers," since they believe that the only legitimate tax is land rent. However, they do typically believe that private property can be created by applying labor to natural resources." 
- Resources for high school teachers and home schoolers: http://www.landandfreedom.org/
- The Henry George Institute: http://www.henrygeorge.org offers free online courses
- Henry George Foundation: http://www.henrygeorgefoundation.org/
- The Council of Georgist Organizations (CGO): http://www.progress.org/cgo
- The Wealth and Want website: http://www.wealthandwant.com/index.htm
Recommended by Kevin Carson of mutualist.org
- Debbie Clark : Her site includes an extended debate over Georgism with libertarian George Smith.
- The Geonomy Society: Forum on Geonomics
- Michael Hudson : Radical economist who has proposed taxes on land value and resource extraction as radical geoist response to neoliberalism in Russia and China.
- Saving Communities : Dan Sullivan's site. Lots of stuff on how geoist taxation can be used to promote progressive ends (especially eliminating urban sprawl, factory farming, etc.) within a free market framework, and on geoist taxation as an alternative to the regulatory state.
- Robert Schalkenbach Foundation : Sells lots of classical Georgist literature.
- School of Cooperative Individualism :
Ralph Borsodi's and Mildred Loomis' organization.
- Dan Sullivan's main page.