Guerrilla Projection!

I saw an exhibition by Shimon Attie a few years ago that featured photographs of projections of the Jewish inhabitants of the Scheunenviertel district in Berlin, dating from the 20s and 30s, onto the walls of Scheunenviertel today. Very powerful, it was like seeing pictures of ghosts.
http://www.eyestorm.com/feature/ED2n_article.asp?article_id=208&artist_id=11966
I did some work as a lighting engineer for a band when I was living in Bath Terrace. I used to practise some of my routines from the rear of my flat, running film loops on two 16mm projectors, and photographs on two 35mm slide projectors across the park onto the rear of the court buildings - I ought to have filmed this.

And there will be a non-guerrilla projection onto City Hall tomorrow night

SE1 Direct - http://www.se1direct.co.uk wrote:

GIANT PAGES OF POETRY PROJECTED ONTO CITY HALL
Friday 7 April
7.30pm-11pm outside City Hall, The Queen's Walk; free
Map: http://quicklink.se1direct.co.uk/?id=931
Over the course of eight nights well-known London buildings,
including the Barbican, City Hall and Somerset House, are
transformed into giant illuminated pages of poetry. As part
of the Beckett Centenary Festival at the Barbican, American
artist Jenny Holzer has been commissioned to present a
series of light projections, For London. Light projections
have been an essential component of her work for a decade,
and this will be the first time they have been seen in
London.
http://www.barbican.org.uk/artgallery
http://www.london.gov.uk

There's a business idea in this! But you need a way to prove it's not Photoshopped.