Cleveland Historic Maps, Finally, someone has stitched together several historic plat maps of greater Cleveland -- for 1852, 1874, 1881, 1898, 1912 and 1920/22 -- and aligned them to allow you to switch between years for any location you select! We've needed this for years. Thanks Chris at ESRI Products.
RailsandTrails.com, Steve Titchenal's wonderful map site, containing a trove of digitized maps, charts, plans, topos, pictures and other historic images.
Western Reserve Historical Society Library - the region's premier historic map collection (Their collection of historic maps of Cleveland and the Western Reserve are now available in their library on color microfilm!)
Bureau of Land Management. "Official Federal Land Records Site." -- Of the three databases offered here, "Land Patents," "Survey Plats and Field Notes," and "Land Status Records," apparently only the first has any Ohio information