The Earthsharing site examines land tenure issues from a geolibertarian perspective, with more emphasis on Green values
The Democratic Freedom Caucus promotes geolibertarian ideas within the Democratic Party.
The Banneker Center for Economic Justice Is a pleasantly entertaining site with interesting materials on economic policies as they relate to land use and taxation.
The Henry George School Gopher Site has a wealth of economic materials about land value taxation and free trade.
The Henry George Institute conducts courses on fundamental economics and free trade issues by mail and by e-mail. It's basic courses are quite good, although it sometimes takes positions that are more geoliberal than geolibertarian.
The History of Economic Thought site is a great source for tracts by economists and economic philosophers.