Phubb
Since 2015-04-01 I'm using my own, self-written and self-hosted PubSubHubbub server called "phubb".
https://github.com/cweiske/phubb
Wordpress
The PuSHPress Wordpress plugin not only implements the publisher side in Wordpress but also the hub part.
It should be able to use it as hub for other pages, too - with a little bit of hacking since
To help keep things simple and limit potential abuse ...[it] will only allow subscriptions ..[of] of the WordPress blog that it is installed on.
Installing Wordpress locally is done in 5 minutes, and using the plugin shouldn't be that hard.
Edit: Yes, that one is on the official hub list and I originally dismissed it since it's not a standalone server, but hey, there doesn't seem to be more.
Drupal
As of 2011-07, there is a drupal module implementing a PuSH hub.