The Historical Society of Pennsylvania, State Library of Pennsylvania, and the Genealogical Society of Pennsylvania have large collections of cemetery and burial records. Copies of many of their records are also at the Family History Library.
The Daughters of the American Revolution (DAR) collection contains tombstone inscriptions from many Pennsylvania cemeteries. This collection is described in the "Genealogy" section. Another important collection is Cemetery Records of Pennsylvania, 9 vols. (Salt Lake City, Utah: Genealogical Society, 1946-1968; FHL book 974.8 V3c; on 3 FHL films beginning with 823929).
A county-by-county list of cemetery record transcripts available at the Family History Library is found under The Church of Jesus Christ of Latter-day Saints, Family History Library (Salt Lake City, Utah), Index to United States Cemeteries (Salt Lake City: Genealogical Society of Utah, 1988; FHL films 1206468-94). Films 1206487-88 include Pennsylvania among other states.
The Place Search of the Family History Library Catalog lists more of these records under:
PENNSYLVANIA - CEMETERIES
PENNSYLVANIA, [COUNTY] - CEMETERIES
PENNSYLVANIA, [COUNTY], [TOWN OR TOWNSHIP] - CEMETERIES