From the Washington Post:

Barack Obama raised half a billion dollars online in his 21-month campaign for the White House, dramatically ushering in a new digital era in presidential fundraising.

In an exclusive interview with The Post, members of the vaunted Triple O, Obama’s online operation, broke down the numbers: 3 million donors made a total of 6.5 million donations online adding up to more than $500 million. Of those 6.5 million donations, 6 million were in increments of $100 or less. The average online donation was $80, and the average Obama donor gave more than once.

By using online means and turning netroots activists into online bundlers and coupling this with a solid showing through more traditional fundraising means, Obama was able to rake in a record amout of cash for his campaign.