Gmail's hiccup this morning that wiped out the world's most popular email program for millions of users across the United Kingdom and the rest of Europe for four long hours highlights the havoc that can be wreaked when the internet is having a bad day.

With companies increasingly relying on web-based applications as the mainstay of their internal and external communications, a relatively small snafu like today's outage can have a much larger effect on business.

Today some gmail users turned to Twitter to carry on correspondence in the interim. One tweet even did some quick math about gmail's decamping: "Let's count the cost: 25m users, 33% affected; average of $50 per hour lost productivity = $415m per hour economic cost..."

But today was nothing compared to what a full-fledged botnet attack could do to the world's computers. Envision malicious software hijacking your computer as your MacAfee remains wholly oblivious, then spreading to computer after computer like fleas on a cur. Want to learn more about a botnet's anatomy? Consult Wired's guide to open-source botnet construction.