This mod let you:
Change different mobs to spawn
You can mine spawners
Disable spawners using redstone
Installation
1. Go to the start, type %appdata%
2. Go to .minecraft > bin
3. Use 7zip or winrar to open minecraft.jar
4. Delete the META-INF folder
5. Copy ALL the ".class" files contained within the mod to minecraft.jar, replacing the existing files.
6. Close minecraft.jar
7. Enjoy the mod.