Alexandria Incident

Alexandria Incidents are massive losses of data that intentionally or unintentionally take down part or the whole of a service's data at once.

Geocities died intentionally, and the loss was the death of the whole service, and thus is considered an A type Alexandria Incident.

The Myspace Data Loss Incident was unintentional, and was the loss of only a portion of the service, and thus is considered a B type Alexandria Incident.

The Tumblr porn ban was intentional, and was a loss of only a portion of the service, and is thus a C type

The Theoretical D type, where the data loss was unintentional and resulted in service wide data loss happens usually to small scale services, or large services in their early days, I do not know of many good examples of this if any

The name, Alexandria Incident, comes from the burning of the library of Alexandria.

another example classification: the death of Flipnote Hatena was an A type Alexandria Incident.

Urbanpedia

An Urbanpedia is website similar to urban dictionary that provides information in a Wikipedia style, while providing the same intent as the information that can be found in the urban dictionary

Encyclopedia Dramatica is kinda like an Urbanpedia.