A very well-done mashup of Monty Python's Knights of the Round Table song with Star Trek visuals:
I had wanted to link to an authoritative copy of this video (it has been uploaded to YouTube a dozen times), but the creators (T. Jonesy and Killa) have no web presence. I think they used to, but took it down for fear of prosecution for copyright infringement.
This video is simply a humorous karaoke, but its heritage is slash fiction, fan-authored fiction about romantic and erotic relationships between same-sex characters in popular culture. The first slash stories involved Kirk and Spock, and the same vidders have created video mashups that hint at these themes, for example, You're So Vain. There are of course other examples out there that are not so subtle.
Perhaps not surprisingly, the entire sub-culture has attracted academic study.