Land.net
   Directory of residential and commercial land for sale or lease.
   http://www.land.net/

Private Islands Online
   Offers listings of islands for sale or rent in the US, Caribbean, Canada, Oceania, and Europe.
   http://www.privateislandsonline.com/

UK Land Investments Group
   Develops parcels of undeveloped land from offices around the globe; includes investment opportunities, market statistics, and news.
   http://uklandinvestments.com