Adams County library, genealogy link can be found by clicking on 'Find Things'.
http://adamsco.lib.oh.us/
Brown County, Union Township Public Library, Ripley.
http://www.ripleylibrary.com/articles/home.asp
Butler County, Hamilton Library, Genealogy can be found in the Database link.
http://www.lanepl.org/
Butler County, Oxford Library,
http://www.lanepl.org/smith.html
Butler County, Middletown, West Chester and Trenton Library.
http://www.middletownlibrary.org/
Clermont County Library, click on 'Research & Homework'. Then click 'Database'. The page it gives you will have a list on the on the side, under Categories is a link to Genealogy.
http://www.clermont.lib.oh.us/
Clinton County, Wilmington Library. Click on 'The Library' then on 'Genealogy'.
http://www.wilmington.lib.oh.us/
Fayette County, Washington Courthouse Library
http://www.cplwcho.org/genealogy.php
Greene County Public Library.
http://www.greenelibrary.info/
American Jewish Archives, in Hamilton County.
http://www.americanjewisharchives.org/
The Public Library of Cincinnati and Hamilton County, click on 'Research & Homework'.
http://www.cincinnatilibrary.org/
Highland County, Greenfield Library.
http://www.highlandco.org/?q=node/12
Highland County, Hillsboro Library.
http://www.highlandco.org/
Highland County, Leesburg Library.
http://www.highlandco.org/?q=node/13
Highland County, Lynchburg Library.
http://www.highlandco.org/?q=node/14
Montgomery County, Dayton Library. Click on 'Subject Guides'.
http://www.dayton.lib.oh.us/
Montgomery County, Dayton.
Wright Memorial Public Library. Click on 'Research Database'.
http://www.wrightlibrary.org/
Montgomery County, Wright State University.
Official repository and archives for local government records for an 11-county area in central southwestern Ohio. Includes Auglaize, Champaign, Clark, Darke, Greene, Logan, Mercer, Miami, Montgomery, Preble & Shelby counties.
http://www.libraries.wright.edu/special/collections/gov_records/
Preble County Library
The Preble County Room is working on a digital project called the Genealogical & Historical Records of Preble County, Ohio, which will involve indexing and scanning county records. Currently the database includes both an index and scanned image reproductions of Preble County Marriage Records and Obituaries.
http://www.pcdl.lib.oh.us/locations/pcroom.html
Main page for Preble County Library.
http://www.pcdl.lib.oh.us/
Warren County, Mary L. Cook Library, check the 'Ohioan Room'.
http://www.mlcook.lib.oh.us/
Warren County, Mason Public Library. I didn't find a Genealogy link but the Database has something's in it that might be helpful.
http://www.masonpl.lib.oh.us/