Let me begin by saying thanks to everyone who offered ideas.
As it turned out, the best examples I could readily find were the
examples in the documentation. Unfortunately, I wasn't able to show
the examples via the projector, but I was able to give a good run down
of what LilyPond was capable of and hand around a few of my better
looking scores. Internet access is expensive at the conference centre,
so I went along with various installers and the documentation tarball
and gave copies to any who wanted it.
One person asked for a copy of the installer there and then, and had a
good read of the docs that night. She was hooked---she'd wanted some
pro-quality typesetting software but wasn't able to afford the usual
suspects. Another gentleman was intrigued when he saw an input file
I'd been working on---he's well into his seventies, but knew a
programming language when he saw one! He'd just laid out AU$600+ for
the latest Finale, though, and was almost disappointed.
Of everyone there, only one person had heard of LilyPond---a
composition student who is into some pretty weird (to me!) stuff. When
I showed him some of the exotic timing LilyPond does well, he was
pretty excited, and wants to give it a go as well.
I was quite proud when somebody got up to show off the latest
Sibelius. He had a score which he sent around, commenting how good the
output was and how it produced publication quality files. Yet it was
full of collisions and other not-very-niceties. If it were a
competition, LilyPond would have won easily.
Although Lily didn't get many takers at the workshop, various comments
I received afterwards suggest to me that the heavy hitters in music in
my denomination are prepared to take LilyPond seriously, even if they
don't use it personally. So for ten or fifteen minutes' work, I think
we had a success!