A SLAVONIC SCRIPTORIUM is being excavated in Bulgaria:

Bulgarian Archaeologists Discover Unique Medieval Byzantine Seal
Archaeology | August 21, 2009, Friday (Novinite.com, Sophia News Agency)

Bulgarian archaeologist, Prof. Kazimir Popkonstantinov, has discovered a unique medieval seal at the site of the Knyazhevski (i.e. "Princely") Monastery near the Eastern city of Varna.

The seal is dated back to the 10th century and belonged to the Byzantine dignitary Antonius, who was an imperial protospatario in Constantinople. Antonius had correspondence with a representative of the Knyazhevski Monastery, who is believed to have been the Bulgarian Knyaz (i.e. king) Boris I (r. 852-889 AD) himself.

The team of archaeologist Popkonstantinov from the University of Veliko Tarnovo has also discovered fragments of Byzantine ceramics and a book lock near the seal, which is seen as a proof that the Knyazhevski Monastery was a scriptorium of the Bulgarian royal family in the 9th and 10th century when the Slavic literature was developed in the First Bulgarian Empire.

During their excavations in the summer of 2009 so far, the archaeologists have discovered very well preserved monastery vaults from the 9th century. They have stated that those vaults were the only ones preserved in Bulgaria from the medieval monasteries, and that the scriptorium of what once was the Knyazhevski Monastery was the only one in the lands of the Byzantine Empire that was preserved so well.

The Knyazhevski Monastery, located in the Karaach Teke area, is believed to have been the largest literary and cultural center in Northeast Bulgaria in the 9th-12th century. The archaeologists have discovered there over 40 book locks, pieces of parchment, lead seals. They believe that some of the disciples of St. Cyril and St. Methodius most likely worked there.

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Some very interesting Old Testament pseudepigrapha survive only or mainly in Church Slavonic, including 2 Enoch, the Apocalypse of Abraham, the Ladder of Jacob, and the Narrative of Lamech (all presumably translated from Byzantine Greek). Bulgarian scribal culture in this period and later was an important factor in their transmission. See Grant Macaskill's online essay, "The Slavonic Pseudepigrapha: An Introduction." Note also the Marquette website on the Slavonic Pseudepigrapha Project, which is down for some reason at the moment, at least from here. For more on important recent developments regarding 2 Enoch, see here and here. And regarding the latter, note that I have since been informed by an expert that Slavists regard the short recension of 2 Enoch as the superior text, so the text of the work is in less doubt than I indicated at the link. The Coptic fragments of 2 Enoch, the Slavonic Narrative of Lamech, and a Hebrew fragment of the Ladder of Jacob are to be translated for the More Old Testament Pseudepigrapha Project, as are some Adam Octipartite traditions found in 2 Enoch and Latin and Old Irish sources. Oh, and I have collected some Slavonic pseudepigraphers here.