X3 Scripts had software for a while that alot of people used.. Not sure how many people still use it since NATs and MPA seem to be the standards now.. Anything else is going to cause you to have a full time staff programmer installing and modifying things to get it to where you want it to be..
if its for some kind of product you could always also go for Commission Junction also.. but who knows how reliable that is compared to running your own thing..