http://goireland.about.com/od/nightlife/a/sessions.htm
Enjoy 
Uilliam
Found a very good session recently while holidaying in the village of Adare in Co. Limerick.
Starts around 9:30 ish every Fri. night at Aunty Lena’s Bar on main street. (http://www.auntylenas.com )
The night I was there, they had pipes,fiddle, accordion,mandolin, guitar and banjo. Nice atmosphere.