Back in the early days of geekdom the grand creators didn't take fan submissions seriously, and they saw the more obsessive fans as a nuisance rather than a source of new content.
But as the presence of pop culture grew ever larger in our lives so too did the presence of fan works that fit right in with the content it was inspired by and based upon, and fan works gained validity in the eyes of the creators.
Now, thanks to some creative and tenacious fans we have pop culture themed LEGO sets, one of the most played multiplayer games of all time Counter Strike, and the entire freakin' Forgotten Realms setting for Dungeons & Dragons!
See 7 Fan Works So Good They Were Adopted By The Creators at Cracked (contains NSFW language)