I've actually considered doing this for a while, since I'm not quite sure I want anyone on the internet to be able to access certain of my fics and I wasn't very willing to create a custom friends group just for those folk who want to read my fiction, since I like my current f-list setup, where those who show an interest in me get friended back and those who don't, don't. I've been planning a Death Eater birthday party fic for a while, and some of the plotlines for the fic that started as my 2006 NaNoWriMo project contain adult themes and material Not Suitable For Children. Even though at present it contains no porn-y bits (and possibly never will), it would be nice to feel comfortable knowing that I have that as an option at my disposal as a writer, should I decide to use it.
Not that I really plan to write anything terribly risque, really. Apart from some threesome/foursome/moresome Death Eater polyamorous orgy fics, that is. ;)
At present, I still plan on releasing "G for Gen" stories under the fic tag in this LJ. I'm in the process of writing an AU story for the raisingharry fic fest in which Lucius and Narcissa take care of Harry as a child, instead of the Dursleys. It'll be squeaky clean in terms of any sexual content, although some other topics may come up that some people may not care for. (Mostly having to do with Malfoy family attitudes with respect to certain persons.) I'll likely release it here, and either cross-post to theentwyfe or link to here from it -- a bit early to decide that, at this point.
It is possible I might need to f-lock even the stories here, since I have no desire to have LJ delete the entire journal because of less than a handful of G-rated posts. If I can safely avoid that, I will, since I would hate to see all Potterverse fic, even the most innocuous, vanish from LJ-land.
I do know one thing, though.
You can't stop the signal.