I don't remember the name of it, it was over a year ago and the next patch to Minecraft broke the plugin and I don't think the creator ever updated it. This was a time before Maps and Compasses so it helped a lot.
I might try and remake an underground garden/hovel that I made on a server back in the early days of Minecraft. I only have one picture of the area, but just imagine what you can see but a little more open and four times the space. The picture: http://i.imgur.com/jH00P.png
I've make four cobblestone pillars lit up by torches surrounding the compound that Ross and I constructed. You should be able to find it if you follow the coast keeping the water to your left from the spawn. It's safe except from spiders, so you'll probably be fine if you're inside.
Also the main gate is a redstone circuit, I have a basic knowledge of redstone but it's probably not as efficient as it could be. If anyone can make it better feel free to tear it down and remake it.