• The annual and statistical reports of the Revenue Commissioners give detailed income distribution data from 1996 to 2002.
• The Department of Finance publishes an annual collection of Budgetary and Economic Statistics.
• Irish business and finance portal with an especially good comment and analysis section.

These are more polemical pieces or analyses from a certain point of view (mainly left):

• The Celtic Tiger ... who's doing the roaring?
• `Tax cuts did not create the Celtic Tiger' [PDF], from the Irish Congress of Trade Unions.