National's Emerald Club program usually costs $50 to join but if you go through Mousesavers (http://www.mousesavers.com/national.html) it's free - thank you, Mary Waring and Mousesavers!
It's definitely worthwhile to join. It can make a big difference in time at the airport.
Hi! I did not pay to join Emerald Club (don't remember if I went thru Mousesavers!)
It is GREAT to go right to "the aisle" instead of waiting in line at the counter. We really enjoy the convenience.