From Box UK (via the long tail blog):

“a survey of business models used by the top Web apps, most of them variations of ad-supported Free and Freemium. In the chart below, the largest segment (ITA) is ad-supported, the second largest (ISV) is Freemium. After that is referral (ITR) and then the sale of virtual goods (IPV), such as the gifts in Facebook.

“We spent a few hours going through the Webware 100 Top Web Apps for 2008, analysing the business model(s) used by each. The chart below shows the results of this survey: 34% use Advertising, 12% a Variable Subscription model, and 8% each for Virtual Products (typically digital downloads), Related Products (typically a large software company offering a free product to attract you to their platform) and Pay-Per-Use.”