I'm in love with Wedding Themes and More, and its suggestions for an Irish-themed wedding.
You may want to dress in formal bridal wear or the bride and her attendants could dress as Irish maids or pixie fairies. The groom, along with his groomsmen, could dress like Irish gents or leprechauns.
But wait, there's more:
Create a rainbow behind the head table from poster board, each end anchored in a large cast-iron pot. Fill the pots full with newspapers then place a circle base on top of this cut from cardboard. On top of the cardboard, place chocolate gold-foiled "coins". Cut the bride and groom's first names from cardboard and color in emerald green. Spread watered glue mix and sprinkle sparkles on the names. Secure to the hang from the rainbow.
Or why not "create a "blarney stone" from paper mache and place just inside the doorway as people enter"?
More ideas here. In all fairity, as our old neighbor would say, in all fairity I must point out that the author notes that this is not actually a traditional Irish wedding. Which leads me to a story. Around the time of the last presidential primaries, I took myself off to Seattle Center to watch the Democratic caucus. I was listening in on a group of Kucinich supporters, and when the leader asked me for my opinion, I uncharacteristically declined to give it, saying that I wasn't a citizen, and was only there to observe. "Where are you from?" he asked. "Ireland," I said, and he grasped my hand. "Welcome!" he said enthusiastically, shaking my hand in earnest good fellowship, "Welcome -- to democracy."