As Barrack Obama and Mitt Romney lay down their swords today, online advertising group ReTargeter has tallied up the amount spent on online advertising over this US election campaign. And it is utterly enormous.

The Obama campaign's lashed out just over $52 million on online advertisements, almost double that of Republican candidate Mitt Romney who spent a not insignificant $26 million online.

Compared to the amount spent jousting online last time around, the total spending has increased by a whopping 251% to $78 million. Check it out.