Xander from “Buffy the Vampire Slayer” has a job in construction, and Anya was a sales clerk.
Earl Sinclair from “Dinosaurs” had a job pushing down trees.
Uncle Bill on Family Affair owned a construction company.
Steve Douglas (My Three Sons) was (IIRC) a defense contractor.
Grace (Brett Butler’s character in Grace Under Fire) was an oil refinery worker.
The Powerpuff Girls are kindergarten students.
The Tick was a freelance adventurer (and houseguest). I can only recall one episode of the animated series (“The Tick vs. Arthur’s Bank Account”) where his source of income was a part of the show.
“COPS” would be boring without the criminals.
Has Fred Sanford been mentioned yet? Or anybody from Six Feet Under? Those aren’t the type of jobs TV viewers envy.
A nitpick: Doesn’t the guy on “King of Queens” drive a UPS truck? (Not actually UPS, but a fake company).
The mom on “Malcolm in the Middle” works at a grocery store. I’m not sure what the dad does.
Does “Sanford and Son” count? They ran a salvage yard, but I don’t know if you’d consider that the “central theme” or not.
A nitpick: Doesn’t the guy on “King of Queens” drive a UPS truck? (Not actually UPS, but a fake company).
The mom on “Malcolm in the Middle” works at a grocery store. I’m not sure what the dad does.
Does “Sanford and Son” count? They ran a salvage yard, but I don’t know if you’d consider that the “central theme” or not.
Actually Chandler recently quit and now is an unpaid intern at an ad firm.
Other then that each and every thing I can think of has been used already. Including Roc, thought I was the only one who remembered that show, although mostly cause I thought the wife was hot. Ok I’ll try one.
Ben Katz did nothing. You might want to fail him since his father was #8 but Ben Katz just mooched…
Fred Flintstone worked for a construction company.
The cast of Baywatch wear very little and run around on the beach, and no, lifeguard isn’t on the list, either.
Cartman’s mom is a crackwhore.
Fred and Ethel Mertz managed an apartment building.
Anya also was part owner of the Magic Box in S6, so she wasn’t just a sales clerk–she managed and ran the whole place by herself.
On “Newhart”, Larry, Darryl & Darryl did “Anything for a Dollar” until they took over running the cafe next door to Dick Loudon’s hotel. On “The Bob Newhart Show”, Elliot Carlin was a real estate mogol.
Mike “The Brady Bunch”) Brady was an architect, as was Alyse Keaton (sp) (Alex P. Keaton’s mother).
On “Buffy”, the late Mrs. Summers ran an art gallery.
Patty Chase on My So-Called Life owned and ran a small printing company. Her husband Graham worked there for a while too, until he decided to go to cooking school and maybe start a restaurant (when the series suddenly ended, grrrrr).
Chris Peterson, Chris Elliott’s character on Get A Life, was a paperboy.
…and propane accesories.
Peggy’s a sub teacher–does that count? Luanne’s a stylist. Comic Book Guy from the Simpsons…owns a comic book store (Android’s Dungeon, IIRC), Groundskeeper Willie is a groundskeeper, Moe runs a bar, Apu owns the Kwicky-Mart (sp?), Duffman’s a mascot, and Phoney McRingRing was an animated telephone who told us the beauty of new area codes.
Fred Flintstone worked in a rock quarry.
Martha and Jonathon Kent are farmers on Smallville.
On Northern Exposure, although Joel Fleischman was a doctor, Maggie McConnell was a bush pilot, Holling VinCoeur ran a bar/restaurant, Shelly worked at the bar and married Holling, Chris bwas a DJ, Heck…everyone had a “different” job. I guess Ed Chigliak with his film student/houseboy/shaman would fit into the 12.
Spongebob Squarepants works as a short order cook at the Krusty Krab.
Tommy Pickles’ dad is an inventor.
Before their careers as castaways, the Skipper and Gilligan on Gilligan’s Island were a excursion boat captain and his employee.
Coach on Coach was a coach. 
StG
You neglected the all-important “homemaker” as one of your t.v. show job categories:
Lucy on ‘I Love Lucy’
Carol on ‘the Brady Bunch’
Samantha on ‘Bewitched’
Edith on ‘All in the Family’
Deborah on ‘Everybody Loves Raymond’
Mr. Kotterr’s wife on ‘Welcome Back Kotter’ (I can’t remember her first name)
Tim Allen’s wife on ‘Home Improvements’ (ditto from above)
Wilma & Betty on ‘The Flintstones’
Marge on ‘The Simpsons’
Peg on ‘Married With Children’ (although she was a deliberately BAD example of the occupation)
Why don’t people in TV shows ever [or hardly ever] watch TV?
Anybody remember “The Brown Hornet” It was the superhero show that Fat Albert and the gang watched on saturday mornings.
Jim Anderson on Father Knows Best sold insurance.
Ralph Kramden was a bus driver.
Ed Norton was a sewer worker.
Alice was a waitress
The crew on the Love Boat was, well, a crew on a boat
Ned Flanders owns a left-handers shop in the mall
As for shows where TV watching is important: The Simpsons, Cheers, West Wing, Friends, All In The Family, Malcolm In The Middle, Wonder Years…