Older Than Radio: Being prepared for every eventuality (imprisoned under a roof? good thing you got a rope-ladder wound around your body beneath your clothes!) was a trademark of the German pre-World War I movie detective Stuart Webb.
Saw: Jigsaw is getting close to being the personification of this trope, to the point where if there is another film, he's going to make the Batman look like a rank amateur. Despite the slight handicap of suffering from being in the final stages of an inoperable brain tumor in the first three films and the slightly more serious affliction of being dead in the following ones, he is STILL able to mastermind the abductions of dozens of people, the creation of ridiculously elaborate traps, training of real and fake apprentices and apparently being able to predict every single action and consequence of all these machinations nearly flawlessly.
Burt Gummer from the Tremors movie series maintains an enormous collection of firearms and survival gear for any contingency, even before giant, subterranean killer worms invade his town. One exchange in Tremors 3 sums up his existence well:
Made even funnier because, if you watch closely, Burt BORROWS a lighter every time he needs one prior to that point.
Marion from Undead is a 'by the book' example of this trope. His preparedness is explained by his previous experience of alien abduction and contact with zombie fish (?). Everyone thinks that he's crazy, until one day...
Mary Poppins: Mary's bottomless bag contains apparently everything... and more. (Under)played for laughs, but this behavior would still fit the trope.
Spy Kids: The watch does everything... except tell time.
Jerry Fletcher (Mel Gibson) from the movie Conspiracy Theory. It's his Crazy Preparedness that actually saves him and the girl when the "Them" really come to his apartment to get him.
Her earlier experiences made Sarah Connor vigilant and just a little paranoid. Terminator 2: Judgment Day also shows that it made her crazy prepared. She pulls into a friend's place on the Mexican border and tells him she needs her "things". This turns out to be a years-buried cache of weapons including a freaking minigun. It's even alluded to that she spent John's childhood arming him with Chekhov's skills.
In Terminator 3: Rise of the Machines, the "supposed" resting place of Sarah Connor is yet another small weapons cache, complete with bullet-proof coffin. She didn't even tell her son.
In The Sarah Connor Chronicles, it is revealed that when she and John move into a new house, every single time that they move, she has apiece of furniture lined with kevlar and the wall behind hollowed out and stacked with guns (creating an effective fortified firepoint in-house), in addition to cases of guns under ever bed.
The Men in Black have not only a gadget and weapon for everything (rocket car, neuralizer, injection that turns you into a fishman, fishing pole that is actually a gun, etc.) but multiple caches of them hidden throughout New York in random apartments and businesses. Several buildings are actually spaceships, which are a result of a cover-up or placed intentionally, but are nonetheless useful. This trope was played with more in the animated series than the films. In the second film, Agent K neuralized himself to protect the MacGuffin of the film (before retiring and being neuralized again), but left clues in case he needed to find it.
In Harlem Nights, Quick prepares for an evening with a rival club owner's girlfriend by stashing a gun under both pillows of her bed. In doing so, he finds the pistol she's already hidden there. When she pulls it on him afterwards, she finds that he took out the bullets, just in case.
Clyde Shelton (Gerard Butler) in Law Abiding Citizen. Granted he had ten years in which to plan and set everything up, but constructing a secret entrance into every solitary confinement cell in a prison displays a crazy amount of preparedness.
Back to the Future Part II: Doc has prepared for monetary needs in any year with an attache case containing money from several time periods.
From The Transporter, you have the transporter. When he breaks the rules and looks in the package, the bad guys blow up his house. That turned out to not be the problem you might think, because he and the devoid-of-personality love interest end up in a tunnel under his house with access to the ocean. Can't get back out of the tunnel? No problem, because he happens to have scuba gear down there. For two people. Even though he's been a loner for years.
The live-action adaptation of Casshern had a slightly amusing sequence in which the Shinzo Ningen (mutants) rise up from the body parts in a pool that was being used to create a new medical miracle in an "unexpected" turn of events. The amusing part comes in when soldiers burst through the door to gun them down and shout something like "Code 27!" Apparently, government forces of the future already have a code specifically designated for zombie/mutants rising up from medical experiments gone wrong, and it's as early as 27 in the code book.
To a degree, The Man in Black from The Princess Bride. Besides being a skilled swordsman, wrestler, and strategic thinker, he just "happens" to have spent the last few years building up an immunity to a particular poison, a vial of which he just "happens" to carry around with him should the occasion arise when he must engage in a battle of wits.
Jason from Mystery Team who manages to create the following disguises: Hobo; Newspaper Reporter; Gentleman; Mexican Plumber; Varsity Athlete; and Lumberjack from things he finds in his backpack.
It's partly due to his... inventiveness in using them, but many of James Bond's gadgets arguably fall under this trope.
Getting chased by a helicopter on a road next to a lake? Good thing your car (a) converts into a submarine, and (b) has a surface-to-air missile that can fire underwater!
Need to make a quick getaway, but bad guys are surrounding your car? Good thing your car can be operated by remote control!
Are the bad guys now chasing you in their own cars? Just push the button to drop dozens of caltrops in their path!
They're stringing a cable across your path now? Good thing Q put a cable-cutter under the Beemer logo at exactly the right height!
Have to drive back through the caltrops you dropped earlier? No worries - your tires are self-inflating!
Mr. Brooks' secret cache of passports and disguises are a whole extra level of Crazy Preparedness on top of his already intimidatingly meticulous methods.
In Superman Returns, when Superman is in the hospital, the camera shifts to a newspaper headline declaring "SUPERMAN DEAD." Then it pans out to show the paper lying on a table next to one that says "SUPERMAN LIVES."
Richard: A little morbid, don't you think?
Perry: I like to be prepared.
Something similar already happened in a film noir by Fritz Lang (probably You Only Live Once), where a newspaper indicates which of three already-prepared headlines is to be used - the one where the protagonist is declared guilty, not the one of him being declared innocent or the one with "Jury Deadlocked".
Dr. Robert Neville in I Am Legend has a pistol in every room, seemingly every cubbyhole that can hold one. Sometimes several. This is INSIDE the home that is behind several ranks of mines, wires, and barricades to protect it from attack. And has self-destruct capability along with an escape bolthole. And as we later learn, the infected are so tenacious, all of this is still not enough to stop them!.Although he still decides to stay in a fragile old house instead of moving to something that has say hard concrete and no windows so one can say that he is more crazy then prepared
Synecdoche, New York has this with Caden's psychiatrist Dr. Davis, as his conversations with her lack a beat between his speech and her response (like she knows what he'll say beforehand). Even taken Up to Eleven when he sees her in public and ignores her sexual advances; he returns to reading a book she wrote, only to discover the rest of the book is blank pages following a message of "I offer my flower to you, and you deny it. This book is over."
General Joseph Colton from G.I. Joe: Retaliation has a lot of weapons hidden in his kitchen, including a pair of grenades hidden in a bowl of fruit. Although he doesn't seem to be think that it's a good idea to move his home from a fragile old house to something involving hard concrete and no windows so he is a bit more crazy then prepared
Prisoners: Keller Dover clearly believes in being Crazy Prepared. His basement is stocked with canned and packaged food, medical supplies, fuel, and bags of lye.
The Punisher shows Frank Castle fortifying his apartment in case of attack.
In the Marvel Cinematic Universe, each film where Tony Stark has a major role highlights that the guy really did think of everything when designing the Iron Man armour. And if he has happened to overlook something or some weakness, it will be addressed in the next version, which he's more than likely already begun designing.