International and National Government Organisations

www.unep.org - UN Environment Programme
www.eea.eu.int - European Environment Agency
http://europa.eu.int/comm/environment - DG Environment
www.environment-agency.goc.uk/ - UK Environment Agency
www.epa.gov - US Environmental Protection Agency
www.defra.gov.uk - Department for Environment Food and Rural Affairs (UK)

Irish Govermental and other Organisations

http://www.environ.ie - Department of the Environment and Local Government
www.epa.ie - Environmental Protection Agency
http://www.pleanala.ie - An Bord Pleanála
www.enfo.ie
www.iema.net
www.enviroireland.com - this is the online version of the environment and waste magazine - good current affairs articles
www.irishlaw.org - this is a UCC based site which provides useful links, up-to-date news and cases and commentary in all areas of law, with specific reference to environment and planning 
www.ireland.com* - The Irish Times Archives from 1996 
www.lawsociety.ie - the Law society website. It is searchable from 1997, and contains some useful articles.
www.barcouncil.ie - this has a number of articles available on line and contains useful papers primarily on planning issues
www.dublincorp.ie
www.hsa.ie - Health and Safety Authority

Legal Links

Ireland

http://www.irlgov.ie/ag/default.htm (access to Irish Statute Book on the web - Irish Legislation from 1922 -1998)
http://www.irlgov.ie/oireachtas/frame.htm (access to Legislation and Bills since 1997 / Dáil debates etc)
www.bailii.org - also covers the Commonwealth
www.firstlaw.ie *

European

http:/www.europa.eu.int/eur-lex/ (access to European Legislation)
http://curia.eu/en/index.htm (ECJ and CFI website - access to judgements)
http://www.europa.eu.int/eur-lex/en/oj/index.html (Offical Journal of the EU - last 3 months)

Publication websites

www.endsreport.com *

* These are subsription services, however you can do some fairly useful initial searches for free.