I've done an awful lot of reading of Irish history recently, patricularly the war of independence/civil war period. For the war of independence there a lot of good, well researched and interesting books out there, such as Hopkinsons book of the same name, Fitzpatricks 'The Two irelands'. Memoirs are good in this period and equally plentiful. Tom Barry, Liam Deasy, Ernie O'Malley (By far the best written, most readible) Dan Breen and Michael Brennan have all written accounts of their experiences. I'm a bit of biography/memoir whore anyway and there are several good bios on Michael Collins (The most obvious been Tim Pat Coogan, but you really need to overlook some of his amateurish ramblings sometimes) and de Valera. Even Séan Mac Eoin and co. have good bio's written about them.
The Civil War unfortunately is less well written about, probably because of a lack of sources. Michael Hopkinson's 'Green against Green' is virtually a textbook, a monument to historical writing. O'Malleys 'The Singing Flame' is a number one must read, as is Liam Deasy's 'Brother against Brother'. Again I'm rambling with the memoir whoring but Tom Garvin, the UCD political scientist wrote a great wee book, '1922, the Birth of Irish democracy'
So yeah, if you can get through that and take a look at the bibliographies you'll still probably realise who much reading you would still have to do!