Credits Brand Products

A lot of times in the media, credits are just words that fade in and out of the video put in during the post production process. So in other media, a common way to have some variety in the credits is to have them actually exist in the world of the characters. The producer's name on someone's index card, the director on that billboard over there... the sky's the limit. Nobody ever notices or comments on these oddly-labeled items.

Examples of Credits Brand Products include:

Anime

Have you ever tasted Baccano! chocolate?
To LOVE-Ru's opening credits. Frying pans, notebooks, tires, the tan line of breasts...
Manabi Straight's OP has the credits spray painted graffiti style onto the setting.
- Also the case for some (but not all) of the credits in the first opening for Bleach.
The Tower of Druaga: The Aegis of Uruk: see for yourself.
- Sword of Uruk also did this, including baseball uniforms with the voice actors' names on them.
Not quite credits, but Paranoia Agent did this each week with the episode title, which would appear on billboards, in chalk scribbles, or as another part of the scenery.
Arakawa Under the Bridge's first opening credits sequence. Combined with Design Student's Orgasm.
The opening credits of Kamichu! - production team members' names appear on an alarm clock, a box of milk, and other items around the main character.

Comic Books

Will Eisner was fond of doing this.
Mortadelo Y Filemon (1958-1968) included billboards of "Chicle Duglas" in the background.

Film

Napoleon Dynamite's opening credits.
- Gentlemen Broncos had the opening credits as the titles of pulp sci-fi novels.
Shrek's opening credits, various swamp muck "coincidentally" seemed to fall in the exact pattern to match the actors' names.
The closing credits for Day Watch are shown on billboards and signs Semyon drives past, or so the subtitles say. The opening credits (not subtitled, at least in English) might be visible as reflections on the windshield of the truck Anton and Svetlana are in. (Can someone who does read Russian confirm/refute?)
In School of Rock, the open credits appear as various posters and on peoples' shirts in the bar.
The closing credits of Employee Of The Month appear on a register's display.
The credits of West Side Story appear as graffiti on walls.
The opening credits of My Man Godfrey are on neon signs as the camera pans through part of New York City.
Kick-Ass features the film's title as a license plate. Since Kick-Ass was already famous at that point in time, it could be there in-universe.
The title for the Toy Story short "Small Fry" is shown as a label on a small box of French fries.
- And the end credits are shown on an overhead fast food restaurant menu sign.

Live Action TV

Episode 28 of Monty Python's Flying Circus. In episode 35, a character reads the credits out loud.
In an episode of Green Acres, the opening credits are burnt onto Lisa's hotcakes.

Video Games

The opening credits of Bayonetta are on headstones in a graveyard. Enzo "marks" director Hideki Kamiya's marker as "his territory" as the prologue proper begins.