The Anthropological Association of Ireland: http://www.anthropologyireland.org/

Archaeological Review Cambridge
The Archaeological Review Cambridge is a bi-annual archaeological journal, run by postgraduate research students of Cambridge University. Their publicaitions are sophisticated, informative and well worth a read.
http://www.societies.cam.ac.uk/arc/home.html

Assemblage: the Sheffield graduate journal of archaeology: http://www.assemblage.group.shef.ac.uk/
Association of Archaeological Illustrators and Surveyors (UK): http://www.aais.org.uk/

Association of young Irish archaeologists: http://www.a-y-i-a.org/

The Discovery Programme: http://www.discoveryprogramme.ie/

Dept. of Environment, Heritage and Local Goverment

A database containing summaries of excavations conducted in Ireland (North and South) from 1970 to 2005.
www.excavations.ie

The Heritage Council :http://www.heritagecouncil.ie/

Institute of Archaeologists of Ireland: http://iai.ie/

Irish townland database: http://www.seanruad.com

Irish placenames database: http://www.logainm.ie/

National Museum of Ireland :http://www.museum.ie/en/homepage.aspx

National Roads Authority: http://www.nra.ie/Archaeology/

Ordnance Survey Ireland:
http://www.osi.ie/
Online Maps (including historic): http://ims0.osiemaps.ie/website/publicviewer/main.aspx#V1,600000,750000,0

Past Horizons.
Everything an archaeologist needs, including  a tool store and a page containing upcoming excavations around the world.
http://www.pasthorizons.com/

Royal Irish Academy: http://www.ria.ie/

Royal Society of Antiquaries of Ireland: http://rsai.ie/

Saving Antiquities for Everyone (SAFE). SAFE is  a non-profit organisation which is dedicated to preserving cultural heritage.
http://www.savingantiquities.org/index.php

Seandálaíocht.com is Brian Dolan's excellent blog and website about archaeology in general. A significant resource- and a brilliant way of passing the time.
http://www.seandalaiocht.com/

University College Dublin

School of Archaeology: http://www.ucd.ie/archaeology/

School of Classics: http://www.ucd.ie/classics/index.html

School of History & Archives: http://www.ucd.ie/historyarchives/index.html

School of Irish, Celtic Studies, Irish Folklore &
 Linguistics Scoil na Gaeilge: http://www.ucd.ie/icsifl/index.html