ScreenDim is my (paid) app for dimming the screen beyond standard OS settings. On OLED devices, it basically does what ScreenFilter does, but I think in a rather more friendly and useful manner, including pre-sets. (On LCD devices, it's much better than ScreenFilter, as it actually dims the backlight, thereby improving contrast and battery life.)
I just finished making a beta of ScreenDim 1.10. The main new feature is Easy Mode which combines the brightness and contrast sliders into one. Currently, Easy Mode only works on Galaxy S2 (including Epic 4G Touch and other versions) and Kindle Fire. You can toggle Easy Mode with Menu | Settings | Easy Mode.
I'd be grateful for any beta test results. To the first ten people who send me useful reports, I'll give give free copies of the paid ScreenDim 1.10 once it's released, as well as free copies of my LunarMap HD and Force2SD apps, if you want them. (Alas, I don't have a gift-code setup arranged, so the free copies won't auto-upgrade.)