Cloud Control
Most of us have Clouds turned off while we're playing Minecraft. They become bothersome while building tall
structures, and they're particularly annoying while playing custom maps that place the ground level higher than
normal.
By default, Cloud Control moves the clouds to y = 191, which I personally find to be an acceptable height.
The config file allows you to set this value to whatever you want, even above the build height of the world (y = 256)