Has any FanFic'd themselves using a pen-name? Not really for the "omg someone fanfic'd me" aspect but more to write "what if" scenarios that you don't want to write into "canon" but would like to explore anyways.
I wouldn't really call it "FanFicing" since I am not a published author, but I use some of my ideas and even the main stories for divergent tales, mostly to explore the characters and world they live in. It is kind of interesting when you figure out better what makes the characters tick outside the story or go into a place that will never be part of the story.
I've got AUs for the novel I'm cowriting, as well as not-yet-canon backstory and snippets of ideas for the future that I had to write down lest they keep me up all night. It's good exercise.
Sometimes when I get stuck on something in a story I write what I called "Chilari stories" in which I use a character with my internet name who represents me as author stepping into the story to have a chat with the characters.
Hmmm. If I wanted to write about some AU situation in my stories, or some pairing that will never happen in my canon, I think I'd write it as myself, declare it non-canonical, and offer it up as a free story on LJ or AO3 or just on my website.
I didn't write stories, but my friends and I did a lot of author-insert roleplaying in our own worlds. A lot of times, it brought up new interesting plot points and helped flesh out our characters. Other times, it was just self-indulgence.