Columbia County GenWeb Project collection of online resources for genealogy researchers
Columbia County Historical and Genealogical Society
Columbia County Message Board read and post messages with other genealogy researchers of this county
Columbia County Naturalization Records Name Index Database #2 covers periods: 1836-1906 and 1930-1956
Columbia County, PA Genealogy Forum read and post messages about your ancestors for this county
Census-Online.com - census transcriptions for Columbia Co.
Interment.net - cemeteries of  Columbia Co.
The Tombstone Transcription Project - cemeteries for Columbia Co; PA
US GenWeb Archives for Columbia County cemeteries, newspapers, wills, military rosters etc recorded online here

Additional Resources

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