The Boeing 707 was built as a major gamble by Boeing in a time when most airlines were still using piston engined airplanes. Boeing bet the entire company on the success of the 707 or (as it was known in the early days for secrecy reasons) the model 367-80. Luckily for Boeing the gamble paid off and the 707 became a best seller. Some 707s are still in service in cargo and the oocasional passenger role.
The complete story behind the 707 barrel roll as the custodian mentions is this:
Tex Johnston, Boeing's test pilot on the 707 (or dash 80) project heard the Boeing executives were going to be playing golf with the press and top airline executives. He hatched a plan to sell the airplane to the press. As the executives played golf Tex flew over the course and rolled the airplane. He then turned around and rolled the airplane again! The press was delighted and Boeing immediately had orders for 707's. Johnston was reprimanded but since the maneuver he performed was perfectly within the airplane's capability (a slow roll such as this is a +1 g maneuver, the airplane never even knew it was inverted) and since it got so many orders he was let off the hook. he did have to promise never to do that again though.
Thanks The Custodian for reminding me of this great story.