Date Variables available?

I've been thinking of a simple way of inserting an expiry date into a standalone presentation (I mean one that is not within an LMS).

Example application - if I made a sample presentation and emailed it out, but I wanted to prevent it being viewed past a certain date.

 I haven't come across any way yet, so I wonder if this method could be used to do that - by coding in the 'currentdevelopment date' into the javascript that Brian demonstrated....and then if I only wanted the presentation to be viewable for the next 2 months say, I would make a sum that took the 'user system date' minus 60, and if it was positive, jump to a branch that ended the presentation (as it was being viewed more than 2 months in the future).

Does that sort of make sense? Sorry, if I've missed a really simple way of achieving the same thing - just haven't found a way yet!

Cheers