Sometimes I wonder why people even include the really racy bits as much as they do in fan fiction. One minute, you're just reading along and getting into some really good plot with an exciting and entertaining villain and then bam! The main characters stop to have sex. So, the whole time they're doing that, you're thinking, "Rrrright... this is hot and all, but can you do that when we're not trying to vanquish the lord of all evil?" It gets almost tedious.
And I'm not trying to be all prudish or high-and-mighty about it, either. Sex scenes can be great. They can be used to great dramatic effect. They can say a lot about the characters. They can be integrated into the plot. Sometimes, they can even be just plain titillating and worthwhile for that reason. But I do feel like fan fiction, in general, includes way more sexual material than it needs to include.
We could also get into a discussion about what constitutes an acceptable level of violence. It's really hard, when writing fan fiction about a show like Buffy, to contain the violence. If you're writing about a vampire or a demon, then you often have to resort to the soap opera trick of panning over to the fireplace or out the window to imply passage of time and then cutting back to the aftermath scene. I mean, vamps and demons in the Buffyverse... they're a depraved bunch. I can't imagine being able to write about Angelus' torture of Giles (or even of Dru) or of Faith's torture of Wes and then still feeling comfortable with the idea of a twelve-year-old reading it.
So, yeah. I guess this could contribute to why no such list of links currently exists. I like that this site is family friendly. I like that we come on here and discuss prophecies and theories and friendships and family relationships and all kinds of different things without really delving too deeply into sex and violence, which are pretty much splashed across every available medium, anyway. I think that's part of what makes the Buffy Boards such a cool community. That said, though, the Buffyverse contains a good deal of mature material, including a good deal of sex and more violence than you can shake a stick at. While I think the sexual nature of most of the fanfic out there could be toned down a lot, I also think that it's really hard to write about the Buffyverse with any semblance of faithfulness to the original text without crossing the family friendly line. It's possible, but it's difficult. I have actually found the challenge to be quite enjoyable. Still, I think work that isn't written for a family friendly site probably is going to fail to meet that guideline.