The Women's Football Final between USA & Japan was the most streamed event in Olympic history

"1.467 Million Video Streams for Team USA-Japan is Most-Streamed Event in Olympic History
More Than 210 Million Total Viewers for the London Olympics, Surpassed Total Viewership for Atlanta for 2nd Most-Watched Event in U.S. Television History
31.9 Million Average Viewership and 18.0 Household Rating for the First 14 Nights of the London Olympics is Most for any Non-U.S. Summer Olympics in 36 Years
22.9 Million Viewers in Primetime Last Night; 13th Time in 14 Nights that Primetime Viewership Topped Comparable Nights from the 2008 Beijing Olympics"

Source:  Press release from NBC, 10th August 2012