Belfast Botanic Inn SunBelfast Hercules Fri, Sat
Belfast Kitchen Bar Sun
Belfast Madden's bar Thurs , Fri, Sat
Belfast McGuinness's Bar May St. Thurs
Belfast Queen's Students Union An Bun a tee Sat
Belfast Rotterdam Bar Tue
Belfast The Eglantine (University Area) Wed
Belfast The Hatfield Bar - Ormeau Road Sat
There's also the John Hewitt bar, around the corner from Madden's which has a session on a Saturday evening.
I've been to that one, and to the one in the Hercules (an excellent session, great group of musicians).
That's all I know about, but try asking Alison, who may know some more.
There's plenty of music to be found, a friend of mine lives locally, I'll email her to ask her some more.
Madden's session is meant to be good too. If you have a car, there are plenty of sessions out in the country to go to too...?
Cheers
Ella