I loved Intermission - thought it was entertaining and original from start to finish (remember the surly girl working behind the counter in Dunnes?!)
I thought 'Inside I'm Dancing' and 'Adam and Paul' were also excellent - dealt with big issues but not in a patronising way.
That's my three but I'll also mention 'The Snapper' which I enjoyed at the time. And 'The Quiet Man' was also excellent as I'm not really into the older films but watched that one rainy Sunday and thought it was a great film.