“The Muppet Movie” (as well as “The Great Muppet Caper”) was always owned by The Jim Henson Company (ITC only distributed the film) until February 2004, when Disney bought the non-Sesame Street/Fraggle Rock Muppets characters and library (as well as the Bear in the Big Blue House franchise).
Pooh's Adventures. A meme that sounds quite regular for a strange mind at first, but when you find out that they have plans for a family-friendly "Pooh's Adventures of Avatar", then everything is ruined.
Join me as I take on the worst and most bizarre of these fan-created crossovers, watching as much as I can and browsing the wiki to see what other ideas they have up their sleeves (and won't bother to complete).