It's a Wonderful Life/Fridge

Fridge Brilliance

 * George never thanks the town for helping him out with the money in the end. This might seem kind of rude, but it makes sense because George is so used to doing things for other people that he simply doesn't know how to react when someone does something for him. This is also illustrated during his "honeymoon" with Mary.
 * It comes across as his being so stunned he couldn't speak.
 * Also, it's not that his friends and family are doing a favor for him. They're thanking him for the many acts of kindness he's done for them all.
 * In the "I want to live again" scene, the snow doesn't begin to fall until George prays to God for his life back. That doubles as a Crowning Moment of Awesome for those who believe.
 * Potter may seem like a Karma Houdini, but bear in mind if angels exist so do Devils.

Fridge Horror

 * In-universe example: George is horrified by how much worse things would be for everyone he knows without him.
 * George helps a bunch of squatters skimp by on cheap housing instead of letting the supposed "villain" win. We even get a glimpse of what this would mean: a bustling nightlife strip that would undoubtedly boost the small town's economy.
 * ...wow. I mean wow. You seem to have missed that the "bustling nightlife strip" was a street full of nightclubs and...shall we say houses of ill repute? That this is all controlled with an iron fist by the "supposed" villain who has a stranglehold over the entire town as he owns EVERYTHING in it? How about that the police are basically turned into a gang under the control of the "supposed" villain? Wow, a boost to the economy sounds worth it.
 * Not to mention that the town in that timeline didn't seem much wealthier than it did originally.
 * Part of the point of this movie is that money isn't everything, you know. Some things are more important--like integrity and charity (old-fashioned sense).
 * Think of Pottersville like this: with George never born, Potter was able to buy out all good institutions like the Building and Loan and now officially owns the town enough to rename and reshape it in his own image. The result is a dark town filled with cheap, trashy, tasteless establishments that people squander all their money on while Potter gets to have all the wealth and power. Which is far from a healthy economy and removes all decency from the town. That these are the kind of institutions Potter deems "nessecary" for HIS town proves that he really is sick in the mind and soul.
 * George provides cheap (but QUALITY) housing by sacrificing his own profits; Potter provides overpriced slums, but he was poor families' only option until George and the Building and Loan created a better alternative. In the Potterville Universe Potter's monopoly was complete - he owned all the businesses and the housing, so the lion's share of the wealth from the so-called "bustling" gin joints and strip clubs would have gone to Potter while the towns' actual citizens would continue to be bled dry and live in horrible conditions.

Fridge Logic

 * Why is George allowing Uncle Billy to handle the money at all?
 * There's a difference between being forgetful and being irresponsible. Also, YOU come up with a way to tell an old man that he's not fit for the duties he's been performing all his life without a really solid reason.
 * That may be for the better, since Pottersville Mrs. Bailey mentions that after the Building and Loan went out of business, Uncle Billy was put in a mental hospital. Whether that's because he's too loopy to be out on his own or because he just didn't know what else to do with himself is probably up for debate.