Three 8-9 th C. Irish manuscripts have recently been digitised and the images provided free online. The work is part of the Early Irish Manuscripts Project at Trinity College Dublin.
At the end of the first paragraph in each of the following webpages, there is a link to the manuscript images:
1. Garland of Howth (TCD MS 56):
https://www.tcd.ie/Library/early-irish-mss/launch-of-the-digital-garland-of-howth/
2. Book of Mulling (TCD MS 60):
http://www.tcd.ie/Library/early-irish-mss/launch-of-the-digital-book-of-mulling/
3. Book of Dimma (TCD MS 59):
http://www.tcd.ie/Library/early-irish-mss/launch-of-the-digital-book-of-dimma/
The Early Irish MS Project is currently digitising the Codex Usserianus Primus (TCD MS 55). You can read more about that here