The whole plot of A Grand Day Out. Late at evening, the stores are closed; and we're out of cheese! The horror! What to do? Skip the evening snack and fight your cheese withdrawal until breakfast? Inconceivable! Hey, the moon is up...
After realizing they hadn't packed crackers into the rocket, Wallace rushes out, scoops up as many packets as possible and makes it back into the rocket just before the fuse detonates.
A meta-example. Wensleydale cheese was in bankrutcy and nearly ended production, but when Wallace mentioned Wensleydale as a favorite cheese, sales skyrocketed and saved the company!
The model train chase. All of it. Especially when Gromit starts putting down track pieces in front of the train while at full speed from a bottemless box of track sections. Not only that, he is able to select the right pieces while doing that to pull off course corrections.
Wallace to Feathers, as he disarms him: "I'll have THAT, if you don't mind, eh?"
A Close Shave
A Close Shave: Wallace and Gromit pursue Preston, driving a truck full of sheep, in their motorbike-and-sidecar. Gromit, in the sidecar, comes loose from the motorbike and rolls off the road and over a 2000-foot drop. One might think this the end of our beloved canine hero, but instead he hits a sequence of buttons in the sidecar, transforming it into a plane, armed with a porridge cannon, and proceeds to make repeated flyby attacks on Preston! Awesome.
The Thunderbirds inspired way Wallace gets into his window washing gear.
Wallace somehow managing to regiment a bunch of usually mindless sheep. Not only does he lead them in an elaborate prison escape for Gromit, but gets them to form themselves on a motorbike (first as a human - er, sheep - pyramid, and then to fit inside an upcoming tunnel).
The rescue scene from "Loaf And Death." Through a bizarre series of events, Wallace, Piella Bakewell, and Fluffles fall into a crocodile exibit in a zoo. Wallace manages to grab hold of the wall with his foot and catch Piella's ankle, but poor Fluffles ends up falling right into a crocodile's open mouth. Then, within literally seconds, Gromit hurtles over the wall, wraps the elastic string of Piella's sunhat around Piella's nose, uses that string to bungee jump into the crocodile's mouth (which he props open with a long loaf of bread to keep it from closing), and grabs Fluffles just in time for the elastic string to pull them both out. The crocodile's mouth closes too late, leaving it blinking in bewilderment as if to say "What the hell just happened?"
The Meaningful Echo is especially awesome. Prior to the fight, Piella had enough of Fluffles betraying her and gave her a vicious backhand. The first thing Fluffles does in the mech is smack Piella one back, with enough force to send her to the other side of the room for that matter. Karma for an animal abuser at its finest.
A meta-example to start things off: When A Matter of Loaf and Death aired, it was the most watched program of that day, beating that year's Doctor Who Christmas special. Let me repeat that. It beat Doctor Who.
The fact that Wallace and Gromit's reference of Wensleydale saved the cheese from going out of business.