This page says that they focus on places associated with the Takahashi brother, but it's got stuff from the entire series (Usui Pass not having had anything to do with the Takahashis, nor the place where Shingo crashed). There's a really nice close-up of the gutter on the third hairpin on Akina/Haruna. Some of these pictures make my reality hurt.
More pics of M-pass: http://www.cnet-ga.ne.jp/wanderer/journey/maze/maze1.html
This guy went out to get gas on New Year's Day, and ended up driving up a mountain!
I think the text on here has some cool comments -- but my eyes are too tired to try and read the miniscule kanji! I will have to come back to explore later. In the mean time, the pictures are cool, and give a little more detail on a couple of signs.
An object lesson to remember that driving cars fast is not just all fun and games: http://members.tripod.co.jp/truenogtz/ziko/ziko.htm These are pictures of this person's accident on M-Pass in his AE91 Levin. (I like the picture of him on the car!)
As a random side note, I'm wondering why the mad photographing fans whose pages I usually use as a reference to get the place names all are calling this site M-pass, rather than by its full name. Not that I'm complaining too much -- this is the first location I've managed to find completely on my own, with no hints at all from any of the Japanese pages. I almost feel like the proverbial cat that ate the canary, I'm so pleased with myself for figuring it out. (See note below on "it takes the smallest things..." I really, honestly am very easily entertained.)
Okay, my eyes are indicating that they are sick of reading navy blue text on a teal background (or light grey text on a dark grey background. Or orange text on a pink background. Or any of several other eye-straining combinations I've run into in my researches.) So I think I'll call it a night now.