Planned Release Date: Late 2013/Early 2014
ExtraGenerators aims to enhance your Minecraft experience by allowing Server Administrators to modify the generation behaviour by either replacing the Generator or adding more Populators. This means that you could modify your existing For example, you could have Sky Islands ripped out from the ground, caves that follow biome style, more advanced structures(multi-level dungeons, actual towns, etc) and more.
Since the plugin is still being planned, the only way to get a working version is to compile it yourself and put that file in your plugins folder. After that, just adjust the configuration to what you need and you should be good to go.
Disclaimer: Custom builds will recieve no support from the team. Please consider waiting for official builds instead.