Armstrong County Assessment List of 1807
Armstrong County GenWeb Project collection of online resources for genealogy researchers
Armstrong County Historical Society
Armstrong County Message Board read and post messages with other genealogy researchers of this county
Armstrong County, PA Genealogy Forum read and post messages about your ancestors for this county
Armstrong County 1830 Census
CensusLinks.com - online censuses for Armstrong Co.
Interment.net - cemeteries of  Armstrong Co.
Revolutionary War Annuities
Tax Assesment List 1807
The Tombstone Transcription Project - cemeteries for Armstrong Co; PA
US GenWeb Archives for Armstrong County cemeteries, newspapers, wills, military rosters etc recorded online here

Additional Resources

Pennsylvania Obituaries enter your Pennsylvania ancestor's name to search obituaries in over 75 million newspaper pages
Pennsylvania Birth Records
Pennsylvania Marriage Records
Pennsylvania Divorce Records
Pennsylvania Death Records