InternetOff is one of those programs where its name tells you everything: it allows you to disable your internet connection with a click.
Why? The authors point out that sometimes you may feel "too connected". There's Twitter, and Facebook, and emails, and instant messages, and YouTube and more, and sometimes the distractions are so great that you can't get any work done.
With InternetOff, though, if you feel this way all you have to do is launch the program from its system tray icon, click "Turn off the internet" and you'll effectively be disconnected (all your internet-related applications will behave as though you're offline).
If you then begin to suffer withdrawal symptoms (or you've finished your real work) then relaunching the program and clicking "Turn on the internet" will restore normal service. (Although InternetOff does also provide the option to ration access, by only turning the internet on for a fixed period - 15 minutes, say - before blocking it again.)
InternetOff isn't implemented as well as we'd like. You shouldn't have to install something as simple as this, for instance: it ought to be portable.
And there's no need to have the program running all the time, either. Sure, it uses less than 6MB of RAM, but it's just not necessary. A single executable which you could pin to your taskbar would have been better.
These issues aside, though, InternetOff does provide a quick and easy way to disable your internet access whenever you like, and if that sounds appealing then it's worth a closer look.