Hi Space Oddity,
This time, to avoid the old conpiracy theories that the 1969 landing did not occur, something should be left up there to prove that humans landed, eg gouging out in the surface of the moon some shape that can be seen from earth in a modest sized telescope, binos or even naked eye. The shape and form could be left to the imagination and would be a nice little forum subject. Bright lights to shine on lunar nights when pointed at earth using stored solar energy would be an interesting idea.
Check out this site. Something was left on the moon that could be seen from earth.
http://science.nasa.gov/headlines/y2004/21jul_llr.htm
Cheers Marty