In Tank Girl, Satan offers the eponymous heroine beer in exchange for a powerful artifact: God's Housecoat. Her shoulder angel argues that the Devil is a rotten bastard, while her shoulder devil tells her to take the beer. She takes the beer, but uses God's Housecoat to cause its next wearer to put all of his energy into charitable causes. When we next see the Devil, he is participating in a televised run for charity to raise money for a children's hospital.
In Finder, an A.I.'s angel and devil are represented by a one and a zero.
A comic features Bart suffering from a moral dilemma, complete with good and bad angels; the good angel knocks out the bad angel by throwing its halo like Captain America's shield, at which point Bart remarks, "It figures that my conscience would suffer from mood swings."
One of the earlier comics has Bart visited by good and bad angels, until he tells the good angel to get lost, and flicks it away.
Tintin has these appear to Snowy and Haddock on different occasions (most often prompted by the presence of whiskey).
Bad Angel: Go on. You know you want to. Good Angel: ... Bad Angel: Well? Aren't you going to say anything? Good Angel: I don't have to say anything. Guy would never do that. He's a hero, after all. Bad Angel:Anti-Hero. Good Angel: Close enough. Guy: I hate it when that guy's right...
Johnny the Homicidal Maniac takes this to a strange place, as there are three major voices talking to him, that comprise about half the supporting cast. These are Psychodoughboy, voice of depression and self-destruction, Mr. Fuck, voice of violence and destruction, and Nail Bunny, voice of reason (or something approximating it). This seems more a metaphor for horrible, horrible, manic depression as much as anything else, although it just keeps getting weirder. And then there's Reverend Meat, voice of emotion, whom Johnny and Nailbunny are opposed to.
The National Lampoon did a number of comic-book stories based on Doug Kenney's high school/college life. One of them is the basis for the Animal House reference below - his shoulder angel probably doesn't help his case by calling Doug by his nickname "Four-Eyes".
In Deadpool's Team-Up with Machine Man, Deadpool experiences this with the angel being represented by his current partner (Machine Man) and the devil is being represented by the Puppet Master, who they were currently fighting. True to his character (as well as Machine Man's partially) Deadpool pictured the angel as a drunk spouting off boring robot logic which quickly devolved to binary code speak.
The DC Thomson strip "Jimmy Jinx (And What He Thinks)" (originally in Buzz, then The Topper, then The Dandy). His angels were called Goodie and Baddie, and appeared in red-outlined thought bubbles.
Dori Seda had them in her autobiographical comic. With the devil wearing a leather corset and stockings.
Michael Turner's Shrugged depicts a world where these angels and devils actually exist and come to Earth from a world called Perspecta to guide and advise people.
A Bec & Kawl strip from 2000 AD subverted this with a Pagan avatar showing up to present a third option when Beccy is finally given the chance to rule the world.
One PS238 storyline involved "cherubs" and "imps", representing Order and Chaos rather than Good and Evil, influencing people's behaviour, and resembling the Good Angel, Bad Angel to those who could see them.
Minnie The Minx from The Beano in one issue had a shoulder devil pop up, with a caption reading "Here's Min's bad side", with the devil encouraging Minnie to commit mischief, and then a shoulder angel pop up with a caption reading "Here's Min's good side". However, in the next frame the angel also encouraged Minnie to commit mischief, with a caption reading "Oh, forgot. Min doesn't have a good side!"
The Powerpuff Girls story "Amoeba Prime" (issue #49) had the Amoeba Boys congealed into a monster amoeba invading an amusement park. Blossom is disguised as a ride barker with Bubbles as an angel (what else?) and Buttercup as a devil trying to sway the Amoeba(s) from riding the rides.
Good Tommy: Go ahead. Do it. That's exactly what I'd expect from you, taking advantage of a drunk woman in her moment of weakness. I bet your conscience won't trouble you for a second.
Bad Tommy: Yeah! Go ahead. Do it. That's exactly what I'd expect from you, taking advantage of a drunk woman in her moment of weakness. I bet your conscience won't trouble you for a second.
In Noob, Gaea is shown to have an ignored/mistreated good angel.
During KnightquestJean-Paul Valley had them in the form of Saint Dumas and his father, the previous Azrael. Unfortunately, this was due to his Heroic Safe Mode kicking into overdrive with no sign of the off button anywhere.
Giant Days: Dark Esther's good and bad angels show up for a page in issue 14 of the ongoing series. Unusually for the trope, they're Esther's own size. Being Esther's good and bad angels, they're a couple of rather fetching, slightly snarky goths.
In "Capt. Sprocket Meets His Greatest Foe Dr. Neutron" in Mad House Comics Digest #5 an angel and devil show up when Captain Sprocket considers running out on a fight which much better superheroes than him are losing.
The third issue of the black-and-white 64-page run of Howard the Duck had an Angel Howard and a Devil Howard argue over whether Howard should save Christmas or ignore the danger and look out for himself.
In Dykes to Watch Out For by Alison Bechdel, a pair of these show up. The devil is a hetero girl with a skirt.