If you would like to avoid long lines at airport security and/or customs lines upon U.S. reentry, you might want to consider one of these 2 Trusted Traveler programs
Which is right for you?
In a nutshelll: TSA PreCheck can get you through security at the gates through an expedited process, while Global entry expedites the customs process when you return AND  includes the TSA PreCheck security screening process  (Global entry automatically qualifies for the TSA PreCheck but not vice versa)

My husband and I chose Global Entry since it expecites both.  A GREAT decision for us,
Why?
My husband travels for business, sometimes flying weekly for several months at a time, within the U.S. 
As you can imagine he wants to get through those airports as quickly as possible--don't we all!  He loves that he doesn't have to take his laptops out (yes, plural, he's an IT consultant) and can keep his belt and shoes on! When we travel together it's both within the U.S. and internationally, so we like the customs part as well.  
This isn't like a frequent flier program where you can take a companion on with you.  All taveling companions must be enrolled. He got Global Entry before I did but it did us no good if he just had to wait for me anyway. Of course he could order the coffee --or Bloody Mary--so it was ready for when I caught up!  Just sayin'....

Both processes are pretty simple and easy to follow information and process are found on the U.S. Customs and Border Protection sites, unter the Travel tab: 

http://www.cbp.gov/

For TSA PreCheck:
http://www.cbp.gov/travel/trusted-traveler-programs/global-entry/tsa-precheck

For Global Entry:
http://www.cbp.gov/travel/trusted-traveler-programs/global-entry