Neopets has a lot of fiction: encyclopedia articles, short stories, a rich world, comics, game premises, and ongoing Story Arcs (known as "plots") which crop up every so often. And, if in need of inspiration, The Neopets Team (TNT for short) lets talented users post Neopets-related articles, novellas and comic strips.
The site has since evolved into a franchise — video games have been released, a now-discontinued Trading Card Game was made, as well as Nickelodeon shorts, a breakfast cereal, and a magazine. Neopets also provides a simple, efficient way of advertising — sponsor games. These games give easy Neopoints, so they're played by a lot of Neopians every day, which provides some good advertising. It's also rather successful with merchandise; McDonald's and Burger King even had Neopets plushies as part of their kids' meals some years ago.
The PS2 game Neopets: The Darkest Faerie has its own page. Special mention goes to the NeoQuest series of RPGs, which have so many tropes they all have their own page. The Neopian Times Writers Forum (NTWF for short) also has its own page, just be careful of the insanity. Lastly, a Gaiden Game to the main Neopets site, Petpet Park, also has a page, though it's since been shut down.