TSTC is not used for scheduled commercial air traffic. Waco Regional is where all the (gasp) regional carriers fly out of. American Eagle and a couple others.
TSTC used to be an AFB, as has been posted. It has a good sized runway and several airlines, as well as the military and NASA, use the airport for repairs, training, etc. Also, Texas State Technical College (TSTC, get it?) uses the airport for alot of its training in the aviation field.
My uncle has a ranch a mile or so from the base (he's down the street from Wings for Christ Int'l (73F)) and always sees large airliners, large cargo aircraft, and military aircraft flying in and out. He often sees AF1 going in and out when George W. goes down to Crawford. I was at my Grandma's in Waco for Thanksgiving and was on my way to my Uncle's ranch when Marine 1 and a backup flew over us.
They even had an AN124 in there a few years back.
I think it's funny that Waco and TSTC are getting all this attention now that Tony Blair has flown in on a 777... GWB flies in there on a regular basis on Air Force 1 and I hear nary a peep on the forum.