You know what I've always wanted, but my searches have led me to believe that it (inexplicably) doesn't exist?
I want a simple site generator. I don't want markdown, I don't want a fancy templating engine. I want some simple templating system that takes in normal HTML and generates pages from simple templates I define. I want to shove in some arbitrary HTML and have it spit out a site using some base templates.
To the best of my knowledge, that doesn't exist. It would be perfect for someone like me who wants to keep a website updated, but doesn't always want to run PHP on the server for something as simple as that.
I implemented a shoddy version of it on my own, but it's far from ideal. I'm pretty astounded there's not a well thought out version of it out there, considering how useful it seems it would be.
It may not be along the lines of what you're hoping for (it may not be simple enough), but I've found Stasis[1] to be a powerful tool for static site generation.
You can write plain old HTML pages and/or fragments, with your desired level or genericity, and then run them through a set of transformations[2] to fill in content, set attributes (e.g. classes, styles, whatever), un/wrap elements, and so on.