instead of hiring qualified help or going DIY, you should hire a clown to do it for you:
http://www.clownsunlimited.com/view_product.php/1/1015
it would make the event way more interesting. and do youtube that if you go that route!
also looking for slideshow material. i was thinking it would be cool to make a slideshow of a particular area (like the Bugaboos or something) and have everyone who has climbed there (I have not unfortunately) show some pics of what they did.
just an idea.