U.S. consumers have spent $26.6 billion online, up 13%, during the first 37 days of the holiday shopping season. The most recent week saw three separate days surpass $1 billion in spending: Monday, Dec. 3 at $1.117 billion, Tuesday, Dec. 4 at $1.362 billion, and Wednesday, Dec. 5 at $1.051 billion. Lots of money is being spent, but how much of that begins with a search on an engine rather than a Web site?