Please tell me one common application for volume textures, I am not TOO familiar with them.

I thought once that they can be quite attractive for storing several maps (diffuse, normal, specular, etc.) into one texture, but after I heared that mipmaps are done also on the layers (e.g. mip0 512x512x4 --> mip1 512x512x2), they were quite uninteresting for me. Isn't it so??

Thanks for your patience.

[EDIT] Or are there other ways to store several maps in one texture without losing layers on mip maps with volume textures??