As far as I know, the largest four-faced clock tower is the one at Allen-Bradley in Milwaukee, WI.
http://en.wikipedia.org/wiki/Rockwell_Automation_Headquarters_and_Allen-Bradley_Clock_Tower

I dunno... I think that Hackers was definitely a movie filled with over-the-top caricatures, but the stereotypes they were based on definitely have a basis in reality. I loved that movie because, much like with the cast of the book MicroSerfs, I knew an iteration of each one of them.