Aluminum Christmas Trees: While this show likes to exaggerate Portland's quirkiness into oblivion, viewers who don't live in Portland are often amused and mystified to discover that a sketch is based on something people really do in Portland. The "canoe dancing" sketch is a great example.
Archive Binge: Happens in-universe in "One Moore Episode", when two characters discover the reimagined Battlestar Galactica and proceed to watch the entire series in a single sitting, without even getting up to go to the bathroom. When they unexpectedly arrive at the end of the series days later, they decide to hunt down showrunner Ronald D. Moore and persuade him to write more episodes.
Cloudcuckooland: Keep Portland Weird indeed. Lampshaded to hell and back in "The Temp", when Fred and Carrie have to show off all of Portland's idiosyncrasies to a temp mayor played by Roseanne Barr.
Cloudcuckoolander: The Mayor of Portland (played by Kyle Mac Lachlan), which isn't surprising given his constituency. Examples include sitting on an exercise ball instead of an office chair, drawing a dog on a Post-It instead of actually taking notes in a meeting, and lending out framed pieces of Native American art. He also clearly carries a grudge against Seattle for overshadowing Portland's Bourgeois Bohemian culture.
Embarrassing Tattoo: Played with: Carrie dates a man with Eddie Vedder's face tattooed on his left arm; however, she's the one who can't stand it, to the point of hallucinating the tattoo as it talks and sings to her. In the end, it's a deal breaker.
... and she starts dating Eddie Vedder himself. Who, in turn, has a giant Ani Di Franco tattoo on his arm.
Everyone Calls Him Barkeep: The Mayor of Portland is only ever referred to as either "The Mayor" or "Mr. Mayor." A book he wrote is credited to "The Mayor of Portland." When Roseanne Barr takes over his position, she is referred to as "Mrs. Mayor"
A couple totally loses their shit over someone tying their dog up outside a restaurant in "A Song for Portland".
Jack McBrayer gets grilled by a cashier and manager for not bringing a reusable bag to a grocery store.
For Inconvenience, Press "1": Any time characters walk into a place of business and the employee who helps them is played by Kumail Nanjiani, expect him to be the walking embodiment of this trope. He will go through every single option available to the customer, in excruciating detail, whether they like it or not.
Foreshadowing / Brick Joke: Once Fred and Carrie finish their Battlestar Galactica binge, they decide to push Ronald Moore into writing another episode of the show. When they look him up in the phone book, they are vocally surprised that he (actually just another man with the name Ronald Moore) just happens to live fairly close by. It sounds like they're just Lampshade Hanging until the end of the episode where they hold a cold reading for the script of their new BSG episode, and one of the performers is "a local actor" who is actually being played by the REAL Ronald Moore.
The Fun in Funeral: Carrie visits the grave of a man she just committed manslaughter against and dances around singing to Fred over the phone.
Furry Female Mane: The female rat, Carrie has a full head of hair, but so does Fred the male rat.
Loony Fan: Gathy (Kristen Wiig), a fan of CatNap, who is terrified of bands she likes getting famous and "leaving" her. They eventually deal with her by incorporating her into the band and changing the name of the band to "Catnapped".
Magical Native American: One shows up in Dave's dream representing the coyotes he and Kath had been yelling at to stop killing neighborhood cats
Manic Pixie Dream Girl: Alexandra, Fred and Carrie's roommate is an odd example. When you're already living in deepest Cloudcuckooland (i.e. Portland), a manic pixie dream girl is the kind of person who coincidentally does things from odd art movements and avant garde music without knowing about the context, or throws away glass bottles because she thinks that homeless Chinese people will steal them if you leave them with the recycling. Also, in a bit of a subversion, Fred and Carrie are surprised to learn they're significantly more culturally literate than she is.
Arguably a case of Inverted Trope. The "homeless people stealing bottles" thing is actually a fairly common complaint in states with a bottle deposit law (such as Oregon).
Medium Blending: "Cops Redesign" and "The Temp" feature shifts to stop motion for sketches about rats in a supermarket.
Name's the Same: After becoming obsessed with Battlestar Galactica, Fred and Carrie seek out series creator Ronald D. Moore... by looking through the phone book and looking for his name. They seem nonplussed by the fact that the Moore they find is a lower-middle-class elderly black man who they have to explain Galactica to in order to convince him to write more scripts for the series.
The real Moore shows up later in the skit, playing a local actor hired for a table reading of the script. The character has never heard of Battlestar Galactica.
The Nineties: As the opening song notes, Portland is where the "Dream of the '90s" is still alive" as a reality.
Women and Women First. The shopkeepers refuse to remove books from shelves for customers, are against alphabetizing the books on the shelves, and so on.
In their first appearance they locked a customer in the store while going to the bank to get $3 in change, discussing whether it might be a good idea to keep some in the store...
A man calls the DMV to ask for a replacement title on his car. The operator tells him that he'll have to be transfered; when the operator finds out that the transfer won't be back in for another hour, he tells the caller that it'll only be a moment. The caller eventually gets a letter in the mail that no, they can't replace his title.
Later subverted in the sketch "DMV Fairytales", when an exceedingly crappy day keeps Carrie from making it to a DMV appointment on time. This trope is expected when she shows up at the DMV after closing, but then it turns out an employee stayed open just for her and wants to soothe her nerves and hear all about how her day went.
Overcomplicated Menu Order: The series includes a sketch in which a starving couple wander into an overly gourmet burger joint and are exhausted by the barrage of options they're forced to navigate just to order a simple burger. They're then forced to start over because the menu changed while they were ordering.
Overly Narrow Superlative: The city recently won the award for "Best Official Website for cities with populations under 700,000 in the Pacific Northwest area". Especially since there are no cities that big in the northwestern U.S. (It is implied to specifically exclude Seattle, the only city with a population close to that and which the mayor has a grudge against.)
Parody Commercial: Since it's sketch comedy, this is often played straight with commercials for local Portland shops, goods, or services.
Ads for the Portland Milk Advisory Board become a Once an EpisodeRunning Gag in Season 3. They tend to show up in the middle of actual commercial breaks.
And then the trope is inverted by an ad for Geico, frequently aired during the show, that is disguised as a Portlandia sketch taking place at the organic restaurant shown in the pilot episode. (Which makes things tricky if you've DVR'd the show and are inclined to skip ads.)
Reality Is Unrealistic: People are often surprised to discover that the show is actually not exaggerating certain political movements and situations very much. Much of the political content espoused by Fred Armisen's "cyclist" character, for example, is actually part of the "cyclist's rights" platform.
Serious Business: At least half the humor is about somebody taking something too seriously. For example, in "The Temp" one member of a hippie conclave decides to get a gym membership. When the others discover this, they act as if he died.