The Interactive Advertising Board says:

Internet advertising revenue in the fourth quarter of 2004 came in at $2.7 billion while full-year revenue totaled just under $9.6 billion -- a 32 percent increase over 2003's total.

(Via Internet Stock Blog, which also has a pithy quotation from an executive of Martha Stewart Living on the value of content: "Distribution channels change, new platforms emerge, but great content always in demand.")