I've unexpectedly been given the day off!

Trying to decide what to do in Dublin today. Not too flush with cash so the cheaper the better (free is best)
Thinking about the National Museum at Collins Barracks - is it any good?
Also thinking about buying a sack of cans with the money I do have and heading to the Pav at trinity for the day. It's probably a bit early for that yet though so maybe some sort of activity/excursion first....
Any recommendations???
Thanks!
Mods: Don't move to Dublin Forum - they is boring^^^^