AutoIt

I won't write much about AutoIt since it's pretty much self explanatory.

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 95, 98, ME, NT4, 2000, XP, 2003 out of the box with no annoying "runtimes" required! You can even make compiled executable scripts that can run without AutoIt being installed!

AutoIt can:

• Provide a general-purpose scripting language for all Windows versions
• Simulate keystrokes (supports most keyboard layouts)
• Simulate mouse movements and clicks
• Move, resize and manipulate windows
• Interact directly with "controls" on a window (set/get text from edit controls, check boxes and radio buttons, select items in drop-down lists, etc.)
• Create complex user interfaces (GUIs)
• Work with the clipboard to cut/paste text items
• Provide a scriptable RunAs function for Windows 2000/XP/2003

It comes with an excellent documentation in russian, german, spanish, italian, and of course english. And if you get stuck you can easily get help on the forum.
AutoIt is free to download, and also features a script editor to help you write your own scripts.