De Barra's on Monday nights (where I was a regular player until recently - the drive down from Cork got to be too much) and there are also sessions in O'Donovan's Hotel and (I think) Shanley's Bar, though I don't know on which nights. De Barra's and O'Donovan's are both in the main street of the town and can be found in the phone book if you want to find out more about what's happening, and Shanley's is near the town centre. There is also a little weekly or monthly "gig guide" published that gives more detailed info. I always picked one up in de B's, but I'm sure either place can supply them. There are also established trad names appearing fairly frequently, so it's just a matter of getting in touch with a couple of the venues down there. Lovely town, well worth a visit - also check out the statue of Michael Collins while you're there.