Ghost World is a 2001 comedy-drama film distributed by United Artists. It was directed by Terry Zwigoff and based on alt comic author Daniel Clowes' graphic novel of the same name. The story focuses on the lives of teenagers Enid and Rebecca (played by Thora Birch and Scarlett Johansson), in the summer after their high-school graduation.
Despite the public release of the final shooting draft of the script both as its own book and its republication in the Ghost World: Special Edition with multiple scenes described that would have made the movie a more faithful adaptation to its source, the DVD's deleted scenes offer very little in terms of deleted/alternate footage and none of the released deleted footage focuses on either of the film's protagonists. 
There is photographic evidence of at least two lost deleted scenes, one of which appears in the Ghost World: Special Edition (the one of Josh and Enid marked 'Scene 73') and the others from DVD box art and promotional materials.
In addition to the pictured scenes which depict Enid and Rebecca watching TV with Rebecca's grandmother and Enid sleeping with Josh, we are also missing an extended version of Rebecca and Enid's conversation in the College Coffee House with more conversation between the girls before and after the Alien Autopsy Guy approaches them which cuts to various fantasies of Enid's reminiscent of those on page 32 of the graphic novel but with Josh substituted for the girls' former teacher. In addition to this, there are also various other one-liner references to the psuedo-love triangle with Josh. It's theorized that these scenes were simply omitted due to them complicating the plot and making the viewers less sympathetic towards Enid when she eventually sleeps with Seymour later on in the film. 
In 2010, following the release of Zwigoff's Louie Bluie and Crumb onto Criterion Collection, there were rumors that Ghost World would also get the criterion treatment and with it we would likely see more, if not all, of the deleted/missing footage.  Unfortunately, this seems to have been nothing more than speculation and wishful thinking on Zwigoff's part with no further news/announcements in the five years since the linked articles.
Missing Website Content/Extras
One website also refers to fake documentaries that appeared on the official Ghost World tie-in website but the website is now defunct and the supposed documentaries no longer accessible.  (The now dead tie-in site's url being at www.ghostworld-themovie.com)
The WayBack Machine can be used to access the main site, but fails to load the video page (as well as several of the other pages) at all let alone any of its content.