Heidelberger Gesamtverzeichnis der griechischen Papyrusurkunden Ägyptens
The HGV is a searchable database of Greek documentary papyrological sources. The database lists bibliographical and other metadata on the papyri rather than the texts themselves (although translations of some texts are available).
The HGV is in the process of being intergrated with the Duke Databank of Documentary Papyri. (See also Integrating Digital Papyrology.)