http://free.ed.gov/ A great starting point with links to huge numbers of online resources
http://www.census.nationalarchives.ie/ Cencus online (1911 and 1901)
http://www.nationalarchives.ie/ The National Archives online
http://www.nli.ie/en/homepage.aspx National Library of Ireland
http://www.osi.ie/ Ordenance Survey Maps
http://www.limerick.ie/CityLibrary/LocalStudies/ Local Limerick history
http://www.limerick.ie/CityMuseum/ The city museum online
http://www.nationalgeographic.com/ National Geographic
http://www.rte.ie/laweb/ RTE Historical Archives
http://dsc.discovery.com/ Discovery Chamnnel online
http://www.bbc.co.uk/schools/gcsebitesize/ Exccelent GCSE resources (History, Geography, business,english, maths etc. etc.)
http://www.guardian.co.uk/science Science at the Guardian
http://www.guardian.co.uk/politics Politics at the Guardian
http://www.enotes.com/ Literature studies
http://www.boards.ie/vbulletin/forumdisplay.php?f=107 Leaving Cert at boards.ie
http://www.rte.ie/exams/countdownto306.html RTE exam advice
http://www.fetacresources.com Fetac Resources
http://www.math.com includes cool tools for maths
http://www.lizardpoint.com includes online questions and worksheet generators
http://www.jamesbrennan.org/ Free maths resources, Algebra ...
http://www.free-ed.net/free-ed/math/algebraMix/obsolete/brenan.asp Free maths online
http://www.bbc.co.uk/learning/adults/ Adult Learning at the BBC
http://www.101languages.net for language learning including irish ( http://www.101languages.net/irish/ )
http://www.talkirish.com includes free online games
http://www.mytutorials.com Business tutorials online with Youtube videos