Seachtain na Gaeilge 2010 in secondary schools.

In my old school, every year there was a show put on for the duration of SnaG (I dunno how your assembly system works, but in mine it was first years on Monday, seconds on Tuesday, etc., all first thing in the morning, and it was then that the show was put on). In it were Irish dancers, singers, comedy acts and a play that usually the TY class put on. We had Aoibheann Ní Shúilleabháin as a maths teacher, so she pulled a few strings and got Des Bishop and Dathaí Ó Sé to come in too. I'm sure you could somehow get in contact with a few gaelgeóirí 'celebrities', through their respective TV channels/record companies/whatever and let them know that you're putting on a show (that is, if you decide to do it) and sell yourself and beg them to come. If you've a local newspaper, contact them about the show (The Echo were practically gagging for stories when we did it) and they might run a few photos. Let the 'celebrity' (/TV channel/record company/whatever) know and it'd probably give you extra ammo, good press and all. The whole thing will create a bit of hype and get people excited.

Ask the art department to help; making posters, maybe murals if you can. There's loads of stuff you can do!