"Lucky" Theme Party?

Horseshoes, clovers( 3 or 4 leafs), rabbit's feet, (use stuffed toy bunnies), lucky pennies, lucky charms, leprechauns, lucky stones, elephants with their trunks raised, ladybugs, rainbows. All represent good luck.

Decorate with St. Patrick's decorations with clovers/leprechauns/pots of gold
Have a scavenger hunt for a pot of gold(foil wrapped chocolate coins). Or have a lucky egg hunt with plastic eggs filled with the coins.

Make a list of celebrities/people who are lucky in their lives, put one name on the back of each person, and then they have to ask the other gueats questions to find out who they are. Winners are first 2 or 3 to identify their lucky person.
Make word search games with the names of guests mixed in. Winner is first to find all names.
If you/your child are crafty, have guests make something lucky, like a dream catcher. Try enchantedlearning.com/crafts/Dreamcatcher.shtml for directions. The craft is their favor.
Fill a jar with pennies. Let all guests drop a slip of paper with name /guess on it in a container. Winner is the closest to the amount in the jar, and gets the jar.
Check the Oriental Trading Company website for inexpensive decorations and favors.
Hope this gives you some ideas.

What about including the opposite of luck-black cats, mirrors, ladders
You could have a Limbo contest walking under a ladder...
Word search using lucky words

or make as many words as you can from lucky thirteen