This issue also comes up when one airline sells an aircraft to another, or when leasing companies must move aircraft around the world. As mentioned, many of the aircraft stop in places like Gander, Shannon, Glasgow, Reyjavik, Dakar, Recife, Honolulu, Anchorage, Pago, Pago, etc, etc., ie, to segment the journey yet not go too far out of the way. Also, there are many "smaller" airports and military bases world wide that see little or no commerical service but are fully capable of handling a 737/32X size airliner. The trick is to move the airliner in the most cost-effecient way possible.
Also, on delivery or transfer flights, the aircraft is very lightly loaded, ie no passengers or cargo, which adds lots and lots of range.....and the distances flown are far greater than in normal operations. Two good examples are stated above, Boeing delivered most of SAS's 737NG fleet nonstop out of SEA
and Hawaiian's 717s could fly nonstop to Honolulu, even if the seats must be removed and an auxiliary fuel tank must be installed.