Normally, there is a freak fortress server up. (I don't know what happened to it.)
Unfortunately, Muselk and Tava are not planning to release the zombies plugin. It's a pity; I really wanted a zombies server too :/
Yeah, donor perks on the server would be pretty great. It would probably incentivize more people to donate as well.
Don't we have some basic rules already?
Ok, so Zombie Fortress is different than the plugin I'm talking about, but I can't actually find the download for this plugin. Here's a video on the plugin, if you haven't seen it: