Census-Online.com - census transcriptions for  Greene Co.
Greene County, OH Genealogy Forum read and post messages about your ancestors for this county
Greene County Surname Index
Greene County, OH Genweb Project a collection of online resources for genealogy researchers
Interment.net - cemeteries for Greene County
The Tombstone Transcription Project - cemeteries for Greene Co. OH
US GenWeb Archives for Greene County cemeteries, newspapers, wills, military rosters etc recorded online

Additional Resources

Ohio Public Records Search find living & deceased family members/relatives including address, phone number, age..
Ohio Birth Records
Ohio Marriage Records
Ohio Divorce Records
Ohio Death Records