I quite like this story on the BBC site about organists slipping secular tunes into their improvisations. I remember being able to pick out Auld Lang Syne in the improv that that the organist played at my last service in my last job. Not that I have ever seen Jim again, but there you go, it is the thought that counts.
Re: Organists
One of my joys at doing an attachment at St P's & G's was the fact that the organist at the early morning service on Sundays used to play this game. I spotted Eastenders in the middle of a thoughtful moment and had a laugh. About the only thing that made me laugh there!