Can anyone recommend a good mod that makes dungeons and nights darker? I want to use torches and "light" from the alteration school, both of which are useless with the current lighting.

I just turn the brightness down. With reduces HUD opacity, works for me. So it's a little darker outdoors, but that kind of goes with weather.
http://skyrim.nexusmods.com/downloads/file.php?id=4323 has over 1500 endorsemants.

http://skyrim.nexusmods.com/downloads/file.php?id=5253

http://skyrim.nexusmods.com/downloads/file.php?id=4323 is my choice.

Edit:
In the newest version Darker Nights and Interiors are separated to optional files.

http://skyrim.nexusmods.com/downloads/file.php?id=822#

Is the one I use

with the vannila plus option