What are some lesser-known attractions in Ireland?

All tourists seem to do the same basic trip: Dublin, Blarney Castle, Ring of Kerry, etc. These are all cool, but when I go to Ireland, I want to see things off the beaten track as well. I know there are some amazing sights out there that most people p right by. Do any of the locals of Ireland or people who travel there frequently know of some hidden gems that are way worth paying a visit?