I think this is the best place for this; though it's not about a parish church but a cathedral, I would really like to make this known;
The History, Architecture, and Antiquities of the Cathedral Church of St. Canice, Kilkenny
By James Graves
Published by Hodges, Smith, & co., 1857
This whole book, including illustrations is available free on Google Books;
It's an extremely fine, detailed, readable account of the architecture, building materials, historic furnishings, and most of all tomb monuments of the cathedral. It's exactly the type of thing you would want for every such ancient church in ireland (and which often exists for a given church but is hopelessly difficult to acquire). It goes through in detail each aspect of the architecture, and then the monuments including engravings of the medieval tomb inscriptions and their translations and then the history of the personages that are known from records etc. It also details some fragments of the famous medieval stained glass that existed in the chancel, which were discovered around the 1850's. the scholarship doesn't seem at all as out of date as you might expect, with one or two exceptions (e.g. -the round tower!). Also, it was written before some significant works were done later in the century (by Deane) but most of the content actually describes features untouched, and when it does not, well is of more interest ipso facto really. The engravings are also top class.
Since most of the stained glass was added later it doesn't deal with this, however, one of the most complete entries in the new Dictionary of Irish Architects http://www.dia.ie
is on none other than St.Canice's, and it details the authors and dates of most if not all of the stained glass windows, as well as the other modern furnishings.
If anyone is aware of other such books for other Irish churches available online please post the info here