Anyone have any good Decorating ideas?

If you have fluorescent lighting in the halls, you can put green cellophane over the plastic that covers the light fixtures. Instant shamrock fun! My residents used to do that in their dorm rooms, and it looked awesome.

Somehow, someway, have Irish music playing in the hall, at least on the day of judging. Also, have some rubber snakes included in your decor since, legend has it, he chased the snakes from Ireland.

Also on the day of judging, can someone dress as a Leprechaun with a fake pot of gold and stand in the hall?

HAH those are great I will do both :)

Put thatches of cut out paper four leaf clovers on the baseboard/wall. Make the actual shamrocks part large so you can see them. A pot of gold (chocolate coins) or gold wrapped hershey kisses.