Tiny Tooons! You got a nice, big, loss over here who is currently headed to youtube.
My favorite episodes of that show were Kon Ducky, Prom-ise Her Anything, K-ACME TV (whichever one had Super Plucky-o Brothers in it), the music episode with Particle Man, the whole How I Spent My Summer Vacation series... and any episode with Fifi, like Aroma Amore. Fifi was my favorite character, though it's probably as well she didn't appear often since she was usually used for Pepe Le Pew-styled episodes (and if not that, then cameos). Nice that one Halloween episode did a shout-out where the guy knocking on the door is a fat dude who's part of the Fifi Fanclub.
The one thing you find a billion copies of, though, are "Istanbul (Not Constantinople)" and "Particle Man", all from the Tiny Toon Music Television episode. They both introduced a lot of people to They Might Be Giants, and they both involve Plucky. Win-win. I liked Kon Ducki mainly for its behind-the-scenes third act (ah, mango juice!). Sweetie and Sneezer always got on my nerves though.
Special mention to Buster and Babs Go Hawaiian since it hints at a Buster and Babs relationship a bit (well, so did Summer Vacation).
Two defining moments of the famous Summer Vacation episode for me are the THUD sound promo and anything involving the psycho hitchhiker:
But one episode I don't see on there is "Homeward Bound". It has Furrball walking out of the rain and looking for a new home, and it's one of those rare sentimental episodes. The ending is beautiful. The episode's similar in tone to "Strung Out Kitty" where Furrball's chasing a hair ribbon.
EDIT: A while ago I used YouTube to watch the banned episode "One Beer" and the rare "Spring Break" episode. In my opinion I wasn't missing out. I never saw "Spring Break" and thought it had to be awesome if it was so rare... but no. Can't win 'em all.