What other manuscripts and information might just be lying about on some shelf, unknown, unwanted?
I decided by hunch to check the itinerary for previous tionóil using the keyword 'discovered' and can up with these entries:
2002:
http://www.celt.dias.ie/english/tionol/synop02.html#ga "New Ogam stones and an old syllabic nasal
Over the last ten years, since the publication of Damian McManus' A Guide to Ogam, a number of new ogam stones have been discovered. Many of these have come to light through the work of the various Archaeological inventories of the different counties. Others have been found during the course of excavation. One of the purposes of this paper is to draw together information on these various finds. The second part of the paper looks at the ogam stone from Andreas in the Isle of Man and re-examines its importance for the history of syllabic nasals in the light of a recent examination of the stone."
2003:
http://www.celt.dias.ie/english/tionol/synop06.html#iw "A newly discovered Irish computus containing Old Irish terminology
On a research trip through Switzerland earlier this year, I discovered a previously unknown Irish computistical textbook from the late seventh or early eighth century in the Benedictine monastery of Einsiedeln. Before this discovery, only two Irish computistical textbooks were known (namely the Munich Computus and De ratione conputandi), so that this find contributes greatly to the knowledge of Irish computistical studies in the pre-Bedan period. Moreover, this newly discovered text contains unique Old Irish terminology. The purpose of my paper is to introduce this new text by summarizing its contents, discussing its provenance and date of composition, analyzing its computistical context, and presenting the Old Irish terminology found therein."
2007:
http://www.celt.dias.ie/english/tionol/synop07.html#dc "The newly-discovered Whitley Stokes collection in the Albertina University-Library in Leipzig
During a recent research trip to Germany I discovered that the Albertina (University Library) in Leipzig has a substantial collection of manuscript notebooks belonging to the great 19th-c. Irish philologist Whitley Stokes. By a process not now known, these notebooks came to Leipzig in 1919 and have lain in the Library there untouched since then. The notebooks contain all of the transcriptions made by Stokes in the course of his long career in Celtic Studies, principally from Irish manuscripts but also from Welsh, Breton and Cornish texts. The dates of all the transcriptions are meticulously noted, so that it is possible to put together a complete chronological record of Stokes's travels and researches, during the half-century of his active career, from the 1860s until his death in 1909. This talk will outline the contents of the notebooks and the importance of this find."
[OK granted the last one is not like major or anything]
And this from 2005:
http://news.ulster.ac.uk/releases/2005/1892.html