Best FF That Provides Truly Useful and Interesting Etiquette Advice: The Isle Is Full of Noises, by The Great Communicator, aka communicator. Master & Commander movie, Aubrey/Maturin. I swear, that tent where Maturin recovered from the gunshot wound sees more action than most bedrooms. Hell, it sees more action than most bedrooms in brothels. Not that I am complaining or anything. Oh, and the etiquette advice answers a question I don't think Emily Post ever addressed: what do I do when I realize that my best friend knows that I'm watching him jerk off? You can decide for yourself whether you prefer Aubrey's answer or Maturin's.
Best FF That Demonstrates That Mutants Should Carefully Consider Possible Abbreviations Before They Choose Their Codenames, Because "Shatty" Is a Fairly Awful Thing to Be Called During Intimate Moments: What Is Already Known, by Janete, aka 3jane and thete1. X-Force, Shatterstar/Rictor. This story features seduction via masturbation, a technique that really should be far more widely used. In, you know, my strictly personal opinion. It also features a few "don't try this at home" moments, but after all, that's why we love fan fiction. Well, one of the reasons. And as for the codename - you can decide for yourself whether you'd rather be called Shatty or Star, if you were a male-alien-mutant-thing. Not an easy choice, and one that could've been totally avoided if the people who created Shatterstar had spared a single second to think about sex. I mean, of course, sex and Shatterstar together.
Best FF That Will Make You Glad You're a Muggle and Can Thus Read Your Porn Online. (Plus, Our Porn Is Evidently *Way* Better Than Theirs.): Four Letter Words, by Breed, aka weatherby. Harry Potter, Draco Malfoy/Harry Potter. Hearing Draco read a smutty novel out loud - doing all the voices and everything - would probably make me swear off sex for life. Not so Harry. There are some priceless details in this story, but my favorite line is this one: "'You'd think the wood would start to get warped or something if you did that all the time,' Ron whispers." No, I won't tell you the context; just go read it, and reflect on the differences between the wizard world and ours. In ours, for example, no one would ever ever ever sit on the floor in a public toilet, but apparently they have spells to keep them from being icky. On the other hand, as I said, we have easy access to excellent porn. I'll leave it to you to decide which you prefer. (Oh, and don't miss the comments on this one; there's a description of a real porn novel that left me choking with laughter.)
Best FF Featuring the Kind of Masturbation You Hope You'll Never Have to Do and the Kind of Names I Hope You'll Never, Ever Call Yourself: Pressure Is Rising, by clionaeilis. Due South, Ray Kowalski all alone. This is a masturbation story that features social and emotional commentary as well as, you know, the whole solo-sex thing; it's amazing how well the author captures that inner voice that repeats things we don't want to hear, over and over and over until we really just want to hit something, especially when it's hot out. And the last few lines are just killers. If you've ever felt like putting in a few minutes with Ray Kowalski, angst, and jerking off, this would be your story.
And if this isn't your kind of story, well - a Certain Person now requires that I offer a happy option with all Due South angst and sadness. Here's the alternate story - just as good, but totally angst-free.
Best FF That Explains Just How Erotic a Totally G-Rated Voice Mail Message Can Be If Benton Fraser Is the One Who Leaves It (and Ray Kowalski Is the One Who Gets It): Flying Solo, by estrella30. Due South, Ray Kowalski/Benton Fraser. Yes, folks, this is the second story that features masturbation in a public toilet, and this time the, um, performer doesn't even have the excuse of being a teenager in a magically germ-free world. But we'll all excuse him, because, hey, it's Ray, and he's in love with Ben, and all is right in the world, mmm? And this is the final decision I'll ask you to make today: you can decide for yourself whether you prefer your masturbating Ray to be angsty or angst-free. (We already know what a Certain Person will choose.)