Was it ever explained how Kramer managed to live in Manhattan with no job? I have seen most but not all episodes of the show. I am just wondering if it was ever revealed how he managed to get by financially.
Well, he hardly ever had to buy food, mooching off Jerry all the time. And it looked like he got most of his clothes at the thrift store. As for rent, he and Newman probably blackmailed the building owner. 
Mostly he “fell ass backwards in money” and “mooched food from his neighbor”, according to George Costanza. Some ways he got money:
*Gambling
*Various theatre projects, like being a stand-in
*His many invention ideas, like the coffee table book brought him good money
*Various entertainment projects, like guest-starring on “Murphy Brown”, being in a Calvin Klein commercial, and being in a Woody Allen movie (he was fired, and I’m not sure if he got paid or not…)
I’m sure there are more.
Didn’t Kramer hold a series of strange jobs? I remember something about him trying to pitch the idea of a coffee table book about… well, coffee tables… to some large publishing house.
And weren’t the Japanese businessmen he stuck in his dresser drawers supposed to be business associates of his?
My impression is that he lives off of a series of scams, business deals of dubious worth, frivolous lawsuits, etc. He’s basically a non-criminal grifter.
FYI, the website of Kenny Kramer (the inspiration for the character on Seinfeld) says, “During the disco years Kenny created an electronic jewelry item that sold so well that Kramer was able to live comfortably long after disco died.” So I always assumed that the TV character did something similar.
He was also a bagel maker on strike for (IIRC) twelve years.
“Hey!..no bagel, no bagel, no bagel, no bagel…”
Although this doesn’t really do much to answer the OP, I feel obliged to finish Agrippina’s “fell ass backwards into money” quote as it is my favorite.
“Kramer goes to a fantasy camp ? His whole life is a fantasy camp! People should plunk down two-thousand dollars to live like him for a week. Do nothing, fall ass-backwards into money, mooch food off your neighbors, and have sex without dating. That’s a fantasy camp!”
- George, in “The Visa”
He does happen to get free coffee for life from one of his frivolous lawsuits.
Didn’t he get $ 20 or so from a bank for their failure to say “Hello” to him or something similar?
He also played the role of patient at medical school diagnostics training.
Thanks! I wasn’t sure of the complete quote, so I just put bits and pieces of it in my post. 
I think most of his money, in the later seasons, came from the coffee table book and from a winning horse in the episode “The Subway”. Not that he was doing too badly before, but I think I remember that those two adventures brought in some serious cash.
Didn’t he invent the Calvin Klein perfume that smelled like a day at the beach?
Or did CK steal it from him?
( I still love the portrait that was done of Kramer, entitled, The Kramer. Hah!)
Kramer also sold his own life story to Peterman, didn’t he?
He saves money by buying in bulk, i.e. beef-a-roni. Hilarity ensues.
And he drove a hansom cab on that episode. On another, he gave a “Kramer reality tour” of the neighborhood.
When I saw her at the supermarket, I felt a burning for her like the burning I would later experience during urination…
Well, he did have that company Kramerica that was developing those oil bladders for oil tankers. That’s got to be worth something.
Great posts! I always kind of assumed that, every once in a while, one of his many scams/deals, etc. would actually pan out for him. Most of them, of course, just provided the viewers with hilarity! You guys reminded me of some classic comedic moments from the show! Thanks!
Then there was the time he and Newman collected all those soda cans and used a mail truck to drive them to Connecticut? to redeem them for a profit. 'Course that didn’t work out.
And the time he and Newman got a jinriksha and were going to use homeless men to pull it. That one didn’t work out either.
I don’t think he made any money from that, because the oil bladder didn’t work (it exploded all over Jerry’s girlfriend).
He also went to a 9-5 job, but didn’t get any pay because he didn’t really work there.