Is anyone familiar with the "Global Entry" program?

Global Entry is a pretty cool CBP program. Keep in mind that DEN doesn't operate that many intercontinental flights since they are in the middle of the US. Most of their international flights are to Canada and Mexico, so if you fly out to European, South American, or Asian destinations, you're more likely to visit another gateway airport before arriving to DEN. Since you have to clear customs at your first point of entry into the country, it may still be worth it... especially if you pay nothing.