Federal Government

Federal Geographic Data Committee
Federal Geographic Data Committee - National GeoSpatial Data Clearinghouse
Federal GeoSpatial One Stop

National Geodetic Survey
National Spatial Data Infrastructure

United States Department of Agriculture - Forest Services
United States Department of Agriculture - Natural Resources Conservation Service
United States Department of Commerce - Bureau of the Census
United States Geological Survey
United States Geological Survey - Center for LiDAR Coordination and Knowledge

State Government

Ohio Department of Development

Ohio Department of Natural Resources - GIMS Program
Ohio Department of Public Safety - Office of Homeland Security

Ohio Department of Public Safety - Ohio Emergency Management Agency
Ohio Department of Taxation

Ohio Department of Transportation - Office of Technical Services
Ohio Environmental Protection Agency

Ohio Treasurer of State

Ohio Treasurer of State - Owned Property Search

Public Utilities Commission of Ohio

 
Local Government

Delaware County Ohio
Fairfield County, Ohio
Franklin County, Ohio

Greene County, Ohio
Lake County, Ohio
Logan County, Ohio
Summit County, Ohio
Westerville City, Ohio

Ohio Coordinating Groups

County Auditor's Association of Ohio
County Auditor’s Association of Ohio - Directory

County Commissioners' Association of Ohio
County Engineer’s Association of Ohio

Ohio County/City Information Technology Association
Ohio Valley Regional Development Commission
Professional Land Surveyors of Ohio

Urban and Regional Information Association, Ohio Chapter
 
GIS Related Organizations/Sites

Geospatial Information & Technology Association
National States Geographic Information Council
Open GIS Consortium Incorporated

Urban and Regional Information Systems Association  

Universities

Cleveland State University - Northern Ohio Data and Information Service

Joint Center for Geographic Information Systems & Spatial Analysis
Ohio University - Institute of Local Government and Rural Development 
OhioView Program
The Ohio State University - Center for Mapping
University of Toledo - Center for Geographic Sciences and Applied Geographics
University of Toledo - UTView

Data Repositories

AmericaView
Microsoft Corporation Terraserver
Ohio Library and Information Network