Kindle Fire users often ask me for the Screen Filter APK, since they don't have the normal Market app. Here's a link to the APK for you (thanks to Drive publishing). Should work for rooted Android and CyanogenMod as well.

As of 12/14/2012 this is version 1.2.1, which includes compatibility for Jellybean 4.2 (finally!). I'll update the file in-place.

It's signed, but for your safety:
Certificate fingerprint (MD5): B2:BC:85:F9:F0:24:7B:C6:BC:2D:B3:68:77:05:B8:B6

Hashes:
$ shasum Screen\ Filter.apk
4eb6ab0f916a979ba1cd41e4a182e48ed5f47d05 Screen Filter.apk
$ md5sum Screen\ Filter.apk
c6e9825ad44211e9eabb1b97db5b2d50 Screen Filter.apk