Within the last 10 years the popularity of the Internet has exploded dramatically. Not one to miss a trick, The Simpsons writers have slipped dozens of internet references and website names into recent episodes. And in fact, several of the websites mentioned as jokes have actually been made by Fox and put online as the episode aired. This page lists all the ones we've found.
A passing reference to this web site was made in A Tale of Two Springfields: Lisa looks up what badgers eat so that she and Bart can lure the badger out of SLH's kennel. The website lists what badgers like (as described in the episode) and don't like; and you can test your knowledge with a game.
From the episode The Computer Wore Menace Shoes, this website is a copy of the gossip website Homer makes. All the stories Homer wrote are here - including the correct wording from the episode, which is a nice touch. Below is the website as it appeared in the episode.
In There's Something About Marrying, The Springfield legalizes same-sex marriage in order to boost tourism. The site appears as it was in the episode, and simply includes a few pictures.
This website was featured in the Season 16 episode Homer and Ned's Hail Mary Pass. Jeff Albertson (Comic Book Guy) has a web site, on which he posts a video of Homer dancing. Three of the links simply show images, but the fourth one shows the Homer clip. There is also a wallpaper and an e-card you can send. Below is the website as it appeared in the episode.
This is a recreation of the college students' website that Bart and Milhouse stumble across during Home Away From Homer. You can see a video clip from the episode and a few pictures.
Dig the Wig '08 was created alongside the Season 19 episode, E Pluribus Wiggum, in which Springfieldians embrace a write-in candidate for the 2008 Presidential elections. The website was not actually featured in the episode, but includes quotes and images from it.
The official Simpsons website from Fox recently received a long-overdue redesign and now looks much better. It has a few nice features, notably the interactive character profiles (see right), and full episodes (if you reside in the US).
However, the rest of the site offers very little, and I strongly advise staying as far away as possible from the "community" section, which is total mess and does not appear to be moderated.
This special site was created in the run-up to the 2000 US election. It details Mayor Quimby's campaign to be the first cartoon character to be elected president; The site includes Diamond Joe's manifesto, campaign trail and a life history. An interesting read.
These two micro-sites appeared shortly before the start of the fifteenth Season, advertising Treehouse of Horror XIV and My Mother the Carjacker respectively. They each contain a short Flash animation of characters from the episode. There were video clips, but they have been removed.