How can I reduce screen brightness below the minimum without an app? I have an Optimus Elite, and it has a minimum brightness setting. In certain apps, I can reduce the brightness below the safe minimum, but when I leave the app, the brightness is increased to the system-wide minimum.

Using RootDim, I can permanently set the brightness below the safe amount, and it will stay even after going to other apps. Or using Screen Filter, I can accomplish almost the same thing even without needing root (it displays a translucent 'filter' over the whole screen, reducing brightness/contrast but not actually changing the backlighting power amount).

What I want to know is where the minimum screen brightness is stored. I have a rooted phone with CyanogenMod 9, so I have permissions to edit anything and could change a config or sqlite entry, but I don't know where this value is stored. What I would like to do is use the status bar brightness slider to be able to slide to the actual minimum of the screen, rather than the OS-controlled minimum. Having an app is useful, but having the functionality without the app seems to be within reach, if only I knew where the OS is getting it's safe minimum setting.

Where is this "safe minimum brightness" setting stored? If I can change it, I can remove my apps and use native controls.
Editing /system/build.prop and changing the ro.lcd_min_brightness property may work.  That property may not exist in your file (It doesn't in the file for my GS3), in which case it will default to 20.  Lower numbers mean lower brightness.

This doesn't actually work on all devices though.  For example, on the Galaxy S2, setting the property to a lower number will allow you to set the brightness control lower, but the actual screen brightness won't go any lower than it did before.

Alternatively, Cyanogenmod includes controls to customize the auto-brightness levels under settings > cyanogenmod settings > display > automatic backlight.  There's an explanation of how to use the custom configuration over here at rootzwiki.