The York County Archives has access to the following indexes online (there's a search function). Patience may be needed for the slow-loading pdf files.
Deed Books, 1749-1912
"Warrant and patent records are held at the Pennsylvania State Archives."
"The following records are also found in deed books; adjudications, articles of separation, discharge of slaves, marriage contracts, mortgages (prior to 1842), ore leases, power of attorneys, releases, right of ways and soldiers discharges."
Grantee / Grantor Indexes, 1749-1912.
Content: The indexes list the grantee, grantor, book, page, date and location.
The deed indexes use the Russell soundex system.From my Which Index Is Which post:
An alpha index using the first letter of one's surname may seem obvious; however, other indexing systems include the Paul Company, Burr Record, Campbell, Cott and the Russell Index. A brief explanation of each of these systems can be found here. Since I've used the Russell Index while researching in Pittsburgh (Allegheny Co, Pennsylvania) which required a steep learning curve on a day when just finding where the deeds where held in downtown Pittsburgh... .