Male Spanking Stories by Tris is a small site dedicated to the works of one author. I've only read a couple of the stories, and can give him a good, but not great review. I honestly think this is a case where he'd be better hosted at MMSA, since his stories don't seem to be related to one another, not yet go beyond MMSA limitations. What he does do is offer a wide variety of story types. While I've only read his spanking stories so far, he also offers a section for 'discipline relationship stories', which is separate from the spanking stories. I've not read any of those yet (actually just discovered that section while trying to learn more about the author), but they might be why he doesn't post on MMSA.
I wasn't able to learn anything about the author in a brief, casual exploration of the site, but I am positive this is not Tristan, who posts on MMSA. His stories are of an entirely different type.
Memories of Childhood Spankings is another site which I can't recommend as whole heartedly as I'd like. The idea is great, but the two stories I've looked at so far weren't anything I'd recommend. They also only have 5 father/son stories. On the other hand, they do offer memories for the other pairings (M/f, F/m, and F/f). As Skater mentioned recently, there are those who enjoy more than just M/m, so I thought I'd mention this site as something new to explore.
Boyz Being Boyz is another site that offers a small collection of stories. They also offer a rather large collection of art work. The stories offered on this site tend towards F/m, though there are a few M/m as well.
For me, the main attraction of this site is the comics selection. They have a number of comics that are X/b, and several more that are mixed. This section appeals to me (beyond the obvious), because of their comics 5, 7, 8, and 11. All of these are selections from Nu West books, published in the 80s. Back in 1985, the only M/M material of which I was aware was Control-T Studios, which was a bit expensive (for a student, at least) and came through the mail. While I had my own box, the mail man would often deliver mail for me (316 1/2) to my dad's box (316), so I was a bit nervous about having anything questionable delivered that way. That meant my only source for /M entertainment was digging through letter columns of gay mags or femdom spanking publications mining for an occasional gold nugget. Even though these cartoons are only of mediocre quality line art and all have F tops, they were heaven for me back then, and I'm glad to see them again.
Finally, Jet's Spanking Fanfics is just what it sounds like. While not all the stories are by Jet (he has a separate listing for a few guest authors) they are all fanfic. What drew me to his site was a story based on Season 4 of Angel, in which Connor spends a lot of time over his Dad's lap. While the spankings aren't as explicit as I might like, they are well written, and the stories themselves are great. If you're not a fan of the subject, you probably won't get into the stories. If you are, I think you'll love them.
Of his own work, Jet concentrates on sci-fi/fantasy TV shows (Andromeda, Supernatural, Buffy, Angel, Charmed), but also includes stories from One Tree Hill, The OC, Summerland, Queer as Folk, Dukes of Hazzard, as the World Turns, and many more). He also has a helpful list that divides the story by who's giving/receiving the spankings (M/m, M/f, F/m, F/f, etc). He also has a lengthy list of links for similar sites.