Along with 'Sick Day', 'Halloweenie' is among my favorite episodes of The Adventures of Pete & Pete. It's one of those episodes of the show I can point to in order to prove to people that this was an incredible, unique kids show that doesn't look or feel like any kids show before or since. Anyway, 'Halloweenie', along with many Pete & Pete episodes, deals with growing up. In this case, Little Pete still loves Halloween and wants to break the record for most houses visited in one night. Standing in his way are the evil Pumpkin Eaters, a group of teens who want to destroy Halloween forever, along with, in a twist, his older brother, Big Pete, who also hates the holiday and feels like an idiot for agreeing to go trick-or-treat with Little Pete because he thinks he's too old. At its core this episode is actually about all holidays, and how as we become adults some of them--Christmas, Easter, and Halloween specifically--just aren't as fun anymore because they're so kid focused. Still, it's a fantastic episode and I usually watch it around this time of year to remind myself of the childhood fun of trick-or-treating.
Retronauts is the totally great retro-gaming podcast on 1UP.com. Though they haven't done an explicitly Halloween themed episode, they once did a podcast about Survival Horror games which is just as good in my book. While this episode has the usual combination of high level criticism, historical context, and very opinionated commentary, it's a fantastic Halloween listen because a large part of the podcast is given over to talk about moments that scared them in games. It ends up having that vibe you get when you gather friends together and you all discuss scary movies or strange, eerie things that have happened in your lives or to people you know. Anyway, here's a direct link to the episode, though you'd probably be better off finding it on iTunes or through the 1UP website. For the sake of ease, it was the 8/23/07 episode though I seem to remember it's listed on iTunes as being the 8/22/07 show.
South Park hasn't had a lot of Halloween episodes, probably because they want to avoid the inevitable Simpsons comparisons. But the handful of Halloween South Parks have been universally great, even the notorious 2006 episode with the "too soon??" Steve Irwin joke. My personal favorite is probably the above pictured 'Spooky Fish' episode with the hilarious Barbara Streisand border, putting the episode in so-called "Spooky Vision." South Park also recently had a Halloween-ish episode that parodies Cloverfield, with giant guinea pigs attacking the world after Peruvian pan flute bands are...you know what, it's silly and complicated and you just have to watch it.
The Simpsons is probably the great grandaddy of modern TV shows--cartoon shows in particular--having Halloween specials. Because these 'Treehouse of Horror' episodes were purposely written to be outside the main "continuity" of the series, it freed the writers and artists to reach for brilliant heights, creating intricate, memorable parodies of well-known horror/sci fi/fantasy films along with Twilight Zone-esque tales. Counting the forthcoming episode from this year, there's been 18 'Treehouse of Horror' specials, all with the established hallmarks like spooky versions of the names in the credits, a different opening sequence often with playful names on tombstones, and the appearance of aliens Kang and Kodos. As these episodes often coincided with presidential elections, there was some great political satire to go along with the fun Halloween stuff.
Penny Arcade, my favorite webcomic, has a habit of producing creative and funny Halloween themed comics. Granted, they don't do it every single year, but if you look back through their archives, you'll fine some good stuff like the above comic about scaring kids with tales of losing a save. It's also worth pointing out the nearly-forgotten 'Fall of The House of Brahe', their only true Halloween story arc to my knowledge, which was most likely produced circa 1999/2000 for GameSpy back when Penny Arcade was doing some of their art. It can still be found here, and I recommend it to newer Penny Arcade fans who maybe didn't know it existed.