John Grenham, the Irish professional genealogist and author, has links to a large number of useful Irish family history websites. There are links to each county in Ireland leading you to sites with information on censuses, church registers, cemeteries, Griffith's Valuation, directories and more. There are also passenger lists and links to family history pages by surname.
https://www.johngrenham.com
Indexes to the Old Age Pension claim forms for Northern Ireland and Donegal. There is a small charge for ordering documents.
http://www.ireland-genealogy.com
This site has more than 19,000 transcriptions of gravestones. There are also photographs of graves and some directories etc.
http://www.from-ireland.net
This website is a wonderful guide to researching Irish family history with very clear explanations of the various topics and lots of useful links. The author, Claire Santry, also has a blog accessible from the site.
http://www.irish-genealogy-toolkit.com/index.html
This site has lots of pages on all aspects of Irish family history research including migration, workhouses, censuses and census substitutes etc.
http://www.rootsweb.com/~fianna/guide
Genealogical gateway for Ireland with information for the whole of Ireland as well as pages for each county.
http://www.genuki.org.uk/big/irl
This site has lots of information for those researching Irish ancestry including Irish history, timeline, maps, pages for each county and lots of links.
http://www.rootsweb.ancestry.com/~fianna/guide/index.html
This site has lots of useful information on how to trace your Irish roots. Part of the British "Moving Here" website.
http://www.movinghere.org.uk/galleries/roots/irish/irish.htm
This website is produced by the Irish Times newspaper. Some information is free and some can be viewed on a pay-per-view basis. Free information includes a surname dictionary, surname histories, place name database taken from the '1851 General Alphabetical Index to the townlands and towns, parishes and baronies of Ireland' and passenger lists. There are also pages for each county and lots of links.
http://www.irishtimes.com/ancestor
Family history gateway for Ireland with a separate page for each county. Many county pages include transcriptions of births, marriages and deaths, directories etc. There is also a surname list with names of researchers.
http://www.irelandgenweb.com