Does anyone know whree I might get hold of some short exerpts of showtunes that I can use for a quiz?

Ta.

Have you thought of CD box sets? I know there's one at the moment, I think it's called 101 Songs From The Musicals. Of course, you'd have to pay for it, but it has loads of different showtunes, from which you could take excerpts

Would www.bluegobo.com be any good for you?

You could use www.mediaconveerter.org and rip from youtube!