I found this website a while back and was able to note the location of several interesting monuments and find them while I was in Ireland in June. This is by no means all the war memorials in Ireland, far from it, but it's an attempt to catalog them. The site was started in November 2004 is run by Michael Pegum of Donnybrook. This is far too large an undertaking for any one person, so he's asking, and getting, contributions from other people. There is a form on the site that people can copy to send him pictures and information on memorials that aren't on his site yet. His goal is to eventually document all the memorials and monuments in Ireland and eventually to hand the website over to the National Museum together with the paper documents on which it is based. That's certainly a great idea and a noble undertaking by Mr. Pegum. Here's info from the home page of the site: 

The Irish War Memorials Project is a developing inventory of war memorials in the Republic of Ireland and Northern Ireland. It includes photographs of each memorial, and details of the sites. With each memorial there is a PDF file with a transcription of the text on the memorial and, in many cases, further information about those whose names appear on them. It should be noted that many memorials carry, as well as those who died, the names of those from the district who served and survived.

There is a database of all of those named, which allows a search for individual persons, with links to the photographs of the memorials. It is also possible to search for all memorials in a particular place or county; for all memorials to a particular war; or for all persons in a particular regiment or service. To find out how to perform these searches, please go to the How to use this site page. All of the text and photographs are free of copyright, but acknowledgement of the origin of any material copied would be appreciated.

The main purpose of the project is to make available, to family historians and relatives, the names of those recorded on war memorials and images of the memorials and the inscriptions. If you find someone of interest to you, please send an e-mail message saying so, to encourage those who contribute to the project. Higher quality photographs can be provided, and it may be possible to answer queries about the memorials themselves. 

http://www.irishwarmemorials.ie/