Windows: We all know your screen is one of the biggest battery drainers on a laptop, but some laptops don't have a built-in button that puts the display to sleep. This little app will do it for you.
Turn Off LCD is just a small executable that turns your display off when you run it. It doesn't run in the background or take up any system resources; it just makes sleeping your display a little bit easier (so you don't have to hit the brightness buttons, or if you're on a desktop, turn the entire monitor off). There's not much else to say beyond that — it's a nice convenience to have! To make it even better, you can turn it into a keyboard shortcut with AutoHotkey. Hit the link to check it out.
Turn Off LCD is a free download for Windows only.
Turn Off LCD [Redmond Pie]