You could always go to the Natural History Museum, or if you like woo, there is a late night ghost bus tour, that has actors and performances en route around Dublin's haunted sights. It capitalises on the fact Bram Stroker was originally from Dublin. Personally I haven't done it yet but people I know who've done it say it's great - even the skeptics!
Hey Allison, Atheist Ireland's pub meetings are normally every 2nd Thurs of the Month so I think you'll be a week too early :(
Tourism-wise, You can buy a day ticket from Dublin Bus City Tours that will drop you off at the main attractions and hop back on when you're done from Museums, Zoo and of course the Guinness Storehouse (Which is Brilliant)