Mortgage advertising is one of the top two revenue generators among financial services for Google, and the industry as a whole is driving a shift in advertising dollars from print and television to the Internet. Expect mortgage online ad spending to overtake television spending by 2009, advised Pete Conti, an analyst with Borrell Associates. While real estate (property listings, brokers, etc) online ad spending will jump 55 percent to $1.8 billion this year, lenders will…