U.S. online local ad spending surpassed US$7.5 billion in 2007, and is predicted to reach $14 billion in 2012, according to research firm Borrell Associates.

In 2007, about two-thirds of spending came from banner and listing, which totalled more than $5 billion. Online video and paid search, on the other hand, only accounted for $2.2 billion, or 29 percent.

However, in 2012, spending on banners and listings will shrink to less than $2.5 billion, while paid search and the rich-media online video format boost to $10.8 billion total, accounting for more than 75 percent of the total spending.

E-mail ads increased throughout the years, but still lag behind all the others as contributing least, according Borrell Associates.