The "Download Now" link directs you to the iTunes App Store, where you must continue the download process. You must have iTunes installed in order to open the link, and you must have an active iTunes account to download the application. This download may not be available in some countries.
From Many Tricks:
Witch allows you to switch directly between not only applications (as you can do with Command-Tab), but windows as well. Instead of switching applications first, then windows, use Witch to switch directly to your desired window. If you're coming to the Mac from Windows, you'll find Witch a natural-feeling replacement for Windows' ability to switch directly to windows. Witch earned a very-rare perfect five-mouse rating from Macworld: "...Witch is easily one of the most useful utilities on my Macs."Witch optionally works across Spaces, too, allowing you to easily switch to windows in any other Space. You can even define global hot keys for useful tasks such as releasing or closing all minimized windows, or zooming the frontmost window.As you can see from the screenshots, Witch has a ton of customization options, none of which are required, but all of which can help make Witch work exactly as you want it to work.Witch was recently recognized as one of Macworld's Mac Gems of the Year for 2010. NOTE: The App Store version of Witch runs as an application (the version available on our web site is a System Preferences panel). You do *not* have to leave the Witch application running, though, to use Witch.The first time you quit Witch, a dialog will appear asking if you'd like Witch to run in the background. Say yes, and you can then switch away without seeing Witch in the Dock. You can access the settings panel at any time by either double-clicking the application, or by pressing comma while the Witch panel is onscreen.