Land Information Field Guides
The National Association of REALTORS® publishes field guides on a wide range of real estate topics.
Access the NAR Resource Field Guides on land topics here:

1031 Exchanges Field Guide
Section 1031 of the U.S. Internal Revenue Code allows investors to defer capital gains taxes on the exchange of like-kind properties.
Access NAR's Field Guide on the process here:

Land Mapping:
Terra Server aerial images around the world
Illinois Aerial Imagery
Iowa GIS mapping data
Minnesota Aerial imagery
Nebraska Aerial Imagery
NRCS Web Soil Survey