Nether Sky

For a more general purpose skybox mod that supports other dimensions, check out Simple Skybox.

(This is a fork of SpaceCandy.)

Adds a skybox to the Nether. Included is a default skybox, with dark clouds and a hellish aesthetic. You should be able to override the textures using a normal resource pack if you want to customize it further.

This mod is completely client-side; it does not need to be installed on servers.

Feel free to submit your own skybox if you want it included in this mod. If I like it, it may become the new default.