Ok, so what I have done so far... (some bits still need testing).
Builder can spawn Stone, Cobble, Glass, Stone Bricks, Glass Panes, wool (all colours) and wooden planks. They can spawn up to 256 in one go by using the giveme command /gme Stone 256
There will then be a 5min cooldown period before you can use the command again.
People in the farmer group have a special ability with eggs. If you throw one at an animal, it will turn in to it's spawn egg allowing you to carry it back and spawn it in your farm.
Miners have the ability to repair their tools and gain exp when they mine.
I really need to edit the first post.