Cork & Kerry Place Names Survey
Irish Local Names Explained - from Library Ireland
Irish Placenames, a Spoofer's Guide
Placenames of Ireland Database - Fiontar (DCU) and The Placenames Branch (Department of Community, Equality and Gaeltacht Affairs)”
Placenames at IrishTimes.com - You can search the entire index of the 1851 General Alphabetical Index to the Townlands and Towns, parishes and Baronies of Ireland, including street listings from Dublin, Cork and Belfast cities, more than 65,000 entries in all.
The IreAtlas Townland Database
Topographical Dictionary of Ireland, 1810 - Has a good list of earlier sources used (p. xvii) and a good glossary of the meaning of Irish place names (p. xxiii).
UK National Archives: Early Irish Maps from State Papers c.1558 - c.1610 - "Over 60 different maps depicting plantations, fortifications and townships in Ireland during the reigns of Elizabeth I and James I, from the ‘State Papers Ireland’ held by the National Archives in the UK." [Location unknown.]