Focusing despite the Internet

For a long time, I have been skeptical of exactly how much increased productivity we can claim businesses really enjoy as a result of the Internet. Don't get me wrong, networked apps, apps deployed in browsers, all helpful tools. But on many occasions I ask myself where we crossed the line.
If, like me, you manage by walking around, it should not be lost on you how many of your employees are browsing non-work websites, doing personal e-mails or exchanging instant messages with their friends (often in the next cube). I don't begrudge some of this, but I could also equally argue for blocking many popular websites and instant message ports at the firewall.
Never one to be a hypocrite, I too lose time to the siren song of the Internet: How's the stock market doing?, for example.
Well even if we are not prepared to visit an Internet-free wasteland on our employees, then perhaps, on occasion, it would be helpful to visit it on ourselves by removing ourselves from the distractions offered by the Internet. A recent article in the Economist introduced me to some new possibilities.
Software is available to block your PC from the Internet allowing you to focus solely on the job at hand. This seems to me like an excellent plan. Probably the best is Anti-Social, which just turms off social networking sites. The category leader is Freedom, a gift at $10. Other contenders worth looking at are Isolator or LeechBlock.
These all work a bit differently. Take a look and comment what you think.