First and foremost, Frank Downey, the ultimate purveyor of fushy muzzy stuff on the Net. These things are so sugary-sweet they're apt to give you diabetes, but it's worth it to see someone who believes unabashedly in rainbows and happy endings. Of course you HAVE to read Dance Of A Lifetime, but while you're at it, my personal favorite is Transcending The Role. Check it out. This guy's awesome.
Next on the list, jfinn. Why? Two words: Amy's Smile. Sweet, memorable, and very fun. And if you're into the gay-male thing, there's plenty of that there too. Too bad she doesn't have a normal personal website to link to.
Nick Scipio is the author of the memorable Summer Camp stories, starring wrestler and camp stud Paul Hughes. These are some of the most memorable characters I've seen in a long time, and Mr. Scipio tells it like it is. Except for maybe the sex. There's so much of it the mind boggles. But that's a plus, right?
The esteemed and honored Reverend Cotton Mather has succeeded in creating a world just as vibrant and lively as Nick Scipio or Frank Downey. You know the author's onto something grand when the story slips out of their control and goes on for pages and pages--or books, in the case of these three--longer than had been anticipated. Follow the ongoing adventures of Sean Porter the Soccer Star. ...If your reading list isn't already full by now.
tenyari maintains the Naked In School collection. As far as anyone can tell, this site links to or hosts copies of every Naked In School story in existence. That's not bad. It was formerly run by Gary Jordan, who currently manages the Silver Clitoride awards (and guest-manages the Golden Clits in the absence of Rui Jorge).
Literotica was the first free-stories site I stumbled upon when I first went searching all those years ago, and I haven't left it since. The only place that competes, in terms of organization and quality, is Stories Online. And of course, there's ASSTR, which probably has more content, but isn't quite as well organized.
brightlyiburn is a promising new author in the field. Though she's hosted at Literotica (which is Stroke-Story Central in comparison with SOL), her stories emphasize character interaction, and intriguing ones at that. With all of the Wolfe family stories she seems to be following a set formula, but it hasn't gotten old yet, and the rest of her stuff goes in all directions. Give her a try.
More to be added as 1) I remember who they are (I've been reading for years!) and 2) I find their webpages.