Taking Liberties Drama Group
Drama League of Ireland
The best resource for any amateur group, not only is it an informative site, they have a links page that will direct you to basically anything you desire (were talking about acting or drama here), probably the most comprehensive amateur Irish drama site on the web, even if Am Dram is not your thing well worth a visit.
Skibereen Theatre Society
The Skibereen Theatre Society have been together since 1985, the site gives you information on there past plays, it also has a photo gallery and info on the Guinness Skibbereen Summer Festival"
A great place to buy those hard to find plays, prices are very competitive as well.