Just to be clear, Cowboy622, John Ringo is a published author of military science fiction. His publisher, Baen Books, has long embraced a policy of DRM-free releases of select older books, mostly from current authors. The link provided by docholladay is to an archive of these releases.
As for websites with stories, there are a large number available with different specialities, content types, and core author/reader bases. At the very least you should check out FineStories.com, a sister site of SOL. FS regulates sexual content allowing a younger audience. As such, many authors prefer that site to SOL, or release on both, since FS has a potentially larger (or at least different) audience.
Literotica.com, obviously, has more of a focus on erotic stories or stories with sexual content than SOL. (SOL allows sex, but does not require it). Personally I'm not a big fan, in part because they have very limited ability to search (about on par with ASSTR in navigation), but some authors who are not on SOL do post there.
The other big site to be aware of for stories is FanFiction.net, for which the type of stories should be obvious. The core base for that site skews a lot younger than SOL, and the site does not allow explicit sexual content, although properly labelled stories can be rated (M)ature: "Not suitable for children or teens below the age of 16 with non-explicit suggestive adult themes, references to some violence, or coarse language.".