This article lists several airports that have activities or attractions close enough to run out and do on long layovers. For nonrevs that might equate to some interesting day trips. Check it out:

<a href="http://www.usatoday.com/travel/columnist/baskas/2007-03...dlife-layovers_N.htm" target="_blank">http://www.usatoday.com/travel/columnist/b...-layovers_N.htm</A>