Invisibility Toggler enables you to view invisible files in the Mac OS X Finder.
The first time you run it, all invisible files will become visible. The next time you run it, invisible files will be hidden again.
Invisibility Toggler is fast, well-developed, remarkably easy to use, doesn't ask you for confirmation each time you run it, comes with complete source code which you can modify for your private use, and the author doesn't demand that you to pay anything to use it (although a small donation is suggested).
The author created Invisibility Toggler specifically because other free programs don't change the visibility setting automatically; they prompt the user first, forcing you to click on a button when all you really want is quick results. If you want to be prompted before the setting is changed, you can either use someone else's program, or if you feel comfortable editing AppleScript code, you can modify the included source code to suit your needs (refer to the "Source Code License" section of the included Read Me).