Dublin

I haven't been since 2005 but...

Dublin Castle - Dame St, Dublin 2, Ireland
Trinity College Dublin - College Green, Dublin 2, Ireland - go see the library and the Book of Kells
Saint James's Gate Brewery - St. James's Gate, Dublin 8, Ireland - Much more than just a brewery tour. Go and have a pint of the black in the Gravity Bar. Top floor 360 degree rotating bar with the best views of dublin.
Merrion Square - Walk around Merrion Sq and check out the doors.
Peter's Pub - 39-40 William St S, Dublin 2, D02 AK50, Ireland - Old style pub for a pint and a sandwich
The Temple Bar - 47-48 Temple Bar, Dublin 2, Ireland - Legendary pub with live trad music and the craic
Dublin Literary Pub Crawl - Go on a 4 pub crawl and be entertained with stories of Oscar Wilde
Oliver St John Gogarty - 18-21 Anglesea St, Temple Bar, Dublin 2, Ireland - Anothe legendary pub with live trad music
Mulligan's - 8 Poolbeg St, Dublin 2, Ireland - 18th century pub with beautiful wood interior
The Brazen Head - 20 Lower Bridge St, Merchants Quay, Dublin 8, Ireland - Oldest pub in Dublin.
Irish National War Memorial Gardens - Islandbridge, Kilmainham, Dublin 8, Ireland - Really nice park and gardens with the Hurling Grounds next to it where maybe you can see some hurling.
Go see a Hurling (Gqaelic football) match at Croke Park. Fastest team sport in the world.
Dublin Zoo is ok but just ok.
St Stephen's Green is a beautiful park

Skerries - An old fisihing village only a few miles north of Dublin that used to be the summer getaway from the city.
The Redbank Restaurant & Guesthouse - 7 Church St, Townparks, Skerries, Co. Dublin, K34 V585, Ireland - One of the best meals we had in Ireland. Worth a nights stay.
Kilkenny Castle - The Parade, Collegepark, Kilkenny, Ireland
Cahir Castle - Castle St, Townparks, Cahir, Co. Tipperary, Ireland - When you look up castles this is the picture
Swiss Cottage - Farrannagark, Cahir, Co. Tipperary, Ireland - up the river from the above castle. They clear cut a swath from the castle to the cottage where they pretended to be peasants and milk maids displacing 200 peasant families in the process.
There is a bar across the street from the castle which I no longer recognize where I sat and ate luch and talked to the bartender about the rules of Gaelic football. "Aye, it was a grand game until they allowed hand passing and now it's all shite." There was also a quick stop store that I walked into to get a bottle of water and such. The proprietor behind the counter said "Sir, you look to have an honest face, would you watch my shop while I step to the back?" "Yes, yes I will." And he left and went to the back to probably piss but whatever. That does not happen here.
Rock of Cashel - Moor, Cashel, Co. Tipperary, Ireland -
Killarney National Park - Expect to see leprachauns riding unicorns and Irlands tallest mountain, yes mountain, Carrauntoohil the highest peak of Macgillycuddy's Reeks
Muckross House, Gardens & Traditional Farm - The National Park, Dromyrourk, Killarney, Co. Kerry, Ireland
Salmon Leap Farm - Killarney, Glenflesk, Co. Kerry, Ireland - Stayed here near Natl Park
Molls Gap, Gap of Dunloe, Wishing Bridge all right around Killarney National Park
The Ring of Kerry - The whole drive is astounding.
The Lobster Bar & Restaurant - Main Street, Waterville, Co. Kerry, Ireland - You've got to eat somewhere why not a resto with a giant lobster on it.
Charlie Chaplin Statue - Main Street, Waterville, Co. Kerry, Ireland - Odd juxtaposition with Chaplin and the sea
Derreenaclaurig Farmhouse Cheese - Derreenaclaurig, Sneem, Co. Kerry, Ireland - If you are driving the Ring of Kerry
Cliffs of Moher - Lislorkan North, Liscannor, Co. Clare, Ireland - you've seen them in the movies now see them for real
Burren National Park - 2 Church St, Knockaunroe, Corofin, Co. Clare, V95 T9V6, Ireland - Land so shitty the Brits let the Irish keep it
Poulnabrone Dolmen - Poulnabrone, Clare, Ireland - Neolithic monument
Moran's Oyster Cottage - The Weir, Roymore, Kilcolgan, Co. Galway, Ireland - Clarenbridge flat oysters in a 250 year old family business
Kylemore Abbey & Victorian Walled Garden - Kylemore Abbey, Pollacappul, Connemara, Co. Galway, Ireland - As beautiful as the pictures
Giant's Causeway, Causeway Road, Bushmills, UK - 44 Causeway Rd, Bushmills BT57 8SU, UK - Get naked and crawl on the to make your own personal recreation of the Houses of the Holy cover.
Belfast - the whole city was fun
Newgrange -
Newgrange, Donore, Co. Meath, Ireland - prehistoric monument

Would highly recommend getting out of the city for a whiskey tour or just a tour of the countryside. Ireland is an amazing country and Dublin was my least favorite part of it. Felt more like a constant stag party than a lived-in city to me. The countryside, however, is absolutely gorgeous.

Dublin (then Dub Linh) was once a Norsemens' city (now Vikings).  It was their main base of military and trading operations in Ireland.  Try to check out that aspect of the wonderful city as well.  

McJeff pretty much covers it. Looking at that vast list, I feel like I sat around doing nothing on our trip there...

Sounds like an interesting read. I may have to pick that up and read it before heading over. Or save it for the plane ride.