In the Whateley Universe, Jade gives Ayla a literal pair of them as a prank... and thereby inspires other students to come up with their own more or less successful versions in turn. The whole thing escalates until the headmistress ends up banning them.
In Periodus, the angel is a positron with a halo and the devil is an electron with horns (1). They don't actually care what's going on; they just love to argue.
Kawaii RanChan on livejournal has an odd habit of adding in her own twist on what she calls her shoulder angels assigned to her by a division of angels in Heaven called Angels Inc., which is a company that assigns guardian angels to people in need. The angels themselves always take the form of characters she likes, OOC or not, that way to actually get her response. It is hinted in a few entries from her good angel that "we're less guardian angels, more invisible friends" — which is all just her own satire about herself. Doesn't make her less crazy.
Subverted on the "Give In" episode of loadingreadyrun, when the main character is trying to decide if he should shoot someone, and he goes ahead and shoots the guy before his good angel has a chance to give his point of view. The good angel is quite annoyed by this.
The AIs in Red vs. Blue play with this trope — there's (usually) only one of them to an individual, but they appear floating over the person's shoulder and exist to help and give advice. If you have a good one, great — you don't have to worry about its evil counterpart undermining its efforts. Unfortunately, that same lack of symmetry means that if you get stuck with an evil one, you're pretty much hosed.
Season 10 gives us an instance of "Bad Angel, Worse Angel" when Gamma and Sigma team up to dupe Carolina into choosing to have two AI implanted into her.
SF Debris gives Janeway these. Befitting his interpretation of her as an insane tyrant, no angel appears. Instead she has a devil, whose advice she dismisses as "religious crap"; an atom, who can only offer suggestions about the behavior of atoms like combining to form a molecule or splitting to release energy; a cowboy, who is terrified and just wants to get out of there (i.e. away from Janeway); and a spider, who always recommends eating people. Initially she goes with shoulder cowboy and decides to leave, and later listens to the devil, who she mistakes for the cowboy because he's now wearing a cowboy hat.
In a later episode she decides to obey the spider, because it's now wearing the cowboy hat. No other advisers appear, suggesting the spider ate them all.
College Humor has a two-minute video where a guy named Chris prepares to masturbate after his roommate leaves. He begins to take off his shorts when his shoulder devil encourages him to jack off naked. When he starts taking his shirt off, his shoulder angel encourages him to keep his pants on in case his roommate returns earlier than anticipated. The conversation goes on until they hear a car pull up. The shoulder angel begs Chris to wait until later, but the shoulder devil gives a heart-warming speech about how there's not going to be a later. Chris and the angel strip naked. And then his roommate walks in.