First of all, the Book of Kells is online, in all its digitised splendour and glory, free for you to look at! Here's the official announcement from the Trinity College Dublin, and here's the direct link to the digital book.
Aarhus Uni Press' free e-book of the month is Re-Mapping Exile (edited by Michael Böss, Irene Gilsenan Nordin and Britta Olinder); it's a collection of essays about aspects of exile in Irish writing.
And finally my discovery of yesterday: The Reallexikon zur Deutschen Kunstgeschichte is available online, for free, under the title of RDK Labor. It works like a wiki in that you can also submit articles, and it's a huge resource of information on German art history.
On a completely different note, it's snowing outside, and - very fittingly - the snowdrops are blooming: