CheShACat's Journal: How to represent at the anniversary of modern computing

I have been asked by an old friend, who is now one of the curators of the Manchester Science Museum, to represent at the upcoming celebrations of the 60th anniversary of Alan Turing's greatest work: the invention of the modern computer. As a long term open source evangelist and lifelong computer addict, this is clearly not an opportunity I can turn down. The question is: what can I do (beyond flashing a desktop cube) to engage youngsters of all ages and hopefully at the same time pass on the free software message to an impressionable and important generation? I believe I can count on the support of my employer and thus I can summon a wealth of workstations if necessary.