AutoIt v3 is a freeware BASIC-like scripting language designed for automating the Windows GUI and general scripting. It uses a combination of simulated keystrokes, mouse movement and window/control manipulation in order to automate tasks in a way not possible or reliable with other languages (e.g. VBScript and SendKeys). AutoIt is also very small, self-contained and will run on all versions of Windows out-of-the-box with no annoying "runtimes" required!
AutoIt was initially designed for PC "roll out" situations to reliably automate and configure thousands of PCs. Over time it has become a powerful language that supports complex expressions, user functions, loops and everything else that veteran scripters would expect.