There is no free lunch, even in cyberspace. Had the industry heeded that little piece of ubiquitous advice during the dotcom boom years, the bust might never have happened. After wasting hundreds of millions of dollars on advertising (does "because pets can't drive!" ring any bells?), the industry learned that the best way to make money online - sans actually selling something tangible - is by selling ad space, not buying it.

Maybe it's no surprise that two of the companies that have learned this lesson best are both sitting in key positions in the industry today: Microsoft and Google. It's also no surprise that these two are each other's biggest competitors in term of managing online advertising.

It's far too early to tell who will win the war, but Google lost one battle last week. Digg.com, which claims it receives over 17 million visitors a month, ditched Google's AdSense, instead opting for a three-year deal with Microsoft to manage its online advertising.

Google has been offering AdSence since 2003. At the time it came out, it provided small business with a way to get their products listed on Google's main search page, but not much has been done to enhance AdSense as a business option since. The price of using AdSence has skyrocketed as competition in the bid-for-prime-position scheme has increased, and click fraud - where competing advertisers can drive up the price of rival advertising by repeatedly clicking on pay-per-click ads - has frustrated many users. Google claims to be aggressively combating this type of fraud.