I've gotten into a routine with the demo's:
Start off with the THX Amazing life demo. That gets people wide eyed because practically nobody is familiar with infrasonics.
Let that roll into the beginning of Transformers 2, the opening scene at the pyramid has got amazingly loud deep bass - the stuff dreams are made of.
Then I usually do the Darla tapping scene from finding Nemo - It's a killer.
And lately I finish off with the dogfight scene in Tron.
I love to see people's expressions during these

Will definitely make a point of watching inception now, haven't seen it because I'm not a Di Caprio fan.