QUESTION: 
What would a human miss the most living on Mars?

ANSWER from Mark Adler on January 29, 1997:
Tough question--you can probably guess as well as I.  There would be many  
aspects of life on Earth missing on Mars (at least early in a colonization).   
My guess is that number one on the list would be the ability to run around  
outside without a bulky pressure suit and life support system.  In other  
words, open space.