Rather, this is about spec TV scripts. One of the writers from Buffy, Jane Espenson, keeps a lovely blog about her writingJane In Progress, where she offers advice to new and wanna-be TV writers.
A couple of weeks ago, she made a post that startled me. I love writing specs, because they're basically professionally useful fan fiction in script format, but I was unaware that some of the more arcane fic-writing and fic-idea techniques might apply. According to Jane, they very well could.
"I recently heard an interesting idea for novel way to approach writing a spec script. It's challenging, fun, attention-getting and probably a really bad idea.
The idea is to do a crossover episode as your spec. You know what I mean -- Dr. House is brought in to help the young doctors of Grey's Anatomy with a tricky diagnosis! Or Ugly Betty's magazine hires the lawyers from Boston Legal!"
Go and read. Crossovers as dangerous but possibly useful professional spec tool. Now I've heard everything. :-)