The Little Pink Book
Helga launches into her first poem of the series
Arnold, on potential owners of the pink book he and Gerald found
Christopher Wahlberg's first ever line in the series...
...and it doesn't take long for his character Stinky to say his first "This really bites"

Field Trip
Grandma's hankering for some turtle soup, and as a bonus, the end credits music (clean and announcer-free)

The List
Sid's first "Boy howdy"

Operation Ruthless
Helga and Phoebe's conversation
The only thing the titular Ruth says in the entire story

The Vacant Lot
Helga's reaction to the Sunset Arms boarders taking over "Gerald Field" (their lot for baseball)

Tutoring Torvald
Torvald extorts money from Sid... and Arnold gets an idea on how to tutor him in math

Gerald Comes Over
Arnold's attempt to get the rent from (the otherwise unheard-from) boarder Mr. Purdy (you're not missing much even without the visual aid, as all they showed was Gerald listening to this conversation from outside Purdy's room)
From one boarder we only know the existence of here, to two boarders we know quite well: Listen to Oskar and Suzie (and the other boarders) duke it out (sucks to be Suzie doesn't it?)

Spelling Bee
Whoa... now that's a big word! Listen to Arnold spelling "onomatopoeia"...
...and then listen in on Helga's ever so improbable miss
Helga yelling "I'm free!" repeatedly

Pigeon Man
Sid's lead in into the legend of "Pigeon Man", and his first use of the phrase "from kid generation to kid generation"
Chill out to the end credits music of this ep, once again, clean and announcer-free

Arnold's Christmas
Stinky: "Hope your Christmas doesn't bite"
Helga's whisper, followed by the end credits music of this ep

Phoebe Cheats
Phoebe reads "the best poem in our class"... but it ain't "hers" she's talking about (and "her" poem wasn't even hers)