SEINFELD
I don't think this one requires explanation. Everyone has heard of Seinfeld, right? The show about nothing. Some people like it, some don't. I think it's a very funny, clever show that got better with time. The characters are probably the most well-crafted characters of any show out there. Most shows "tweak" their characters to drive the plot or manipulate laughs. That's a pet peeve of mine. (See Friends) But on Seinfeld, the characters were consistently neurotic and flawed and funny. It was a great show, period.
MY TOP 5 EPISODES...at the moment...could change at any time:
#5 The Limo
(season 3)
George and Jerry pretend to be "Murphy" and "O'Brien" to get a limo from the airport. Unfortunately, the limo is taking them to a Neo-Nazi rally where O'Brien is giving a very controversial speech.
(season 9)
Genius finale. It could not have been any better. For those who trashed it, what's YOUR big idea for a Seinfeld series finale? I dare you to come up with something better. It can't be done.
#3 The Puerto Rican Day
(season 9)
Because of a huge Puerto Rican Day parade, Jerry, George, Elaine, and Kramer get stuck in standstill traffic. All kinds of funny stuff happens.
Here's a favorite scene:
#2 The Abstinence
(season 8)
Abstinence makes George a genius and Elaine an idiot. Kramer turns his apartment into a smoking lounge.
Clip of smart George w/Derek Jeter and Bernie Williams of the NY Yankees:
#1 The Burning
(season 9)
Jerry becomes obsessed with finding out his girlfriend's mysterious "tractor story". Elaine finds out Puddy is religious. Kramer takes a job acting out illnesses for medical students but does so well he gets typecast. George learns the art of going out on a high note. My favorite parts of the episode are: Kramer's over-the-top gonorrhea portrayal, Puddy and Elaine's conversation about going to hell, and Seinfeld's phone call to his girlfriend.
Other noteworthy episodes:

The Van Buren Boys
The Betrayal
The Pilot
The Bizarro Jerry
The Opposite
The Outing

The Stall
The Voice
The Merv Griffin Show
Where you can see this show: Weeknights on FOX and TBS - check your local listings!