As some may have already been suspecting for a while, the Overviewer project is basically over. The application has been unmaintained for a while now, and we don't plan on changing that.
If you're looking for an alternative, look into BlueMap. It's faster, supports mod blocks, and renders an actual 3D view of the map. It's better than Overviewer could ever hope to be.
The Overviewer website and repository will remain online "as-is". We spent some time reducing technical debt in our web service's setup to rip out all the overcomplicated parts and replace them with static pages; buildbot is gone, the last Windows binaries and the source tarball are now fixed links.
There's no point in "reviving" Overviewer, as doing so would require a complete rewrite of the codebase to make it even remotely maintainable again. At that point, just use a different tool (like BlueMap!) instead.
If you've used Overviewer in the past, or are even still using it (why?!) then we thank you for the trust you put in us.
So long, and thanks for all the fish.