Allow this figure to sink in for a moment; Obama has 13 million email addresses of supporters.

More than 3 million of those people gave money to his campaign. That is a well of support he can draw from for a variety of uses - a tactic he is already taking advantage of as he is continuing to send out appeals to his email list for funds.

Those 13 million names represent about 10% of the electorate that went to the polls on election day. And it is a list that is only going to grow over the next 4 years.

What can President Obama do with that list? He can swamp Congress with emails, phone calls, and letters requesting members to support him on any issue he chooses. It may, as this article in Bloomberg points out, change the entire political landscape:

``It could be life-changing for American politics,'' said conservative activist Richard Viguerie, a pioneer in using direct mail for political causes. ``It allows Obama to be independent of everybody.''

Obama's collection of e-mail addresses is just one example of how he has used technology to change the way political campaigns are run. He has used his Web site to solicit suggestions, announced his selection of Senator Joe Biden as his running mate through a text message to supporters, and bypassed conventional media by using Facebook, MySpace and YouTube.

``The whole thing has been about building relationships,'' said Joe Rospars, the Obama campaign's director of new media. ``None of that is going to end on Election Day. People are going to be hungry to find a way to make good on all the promises that we've all collectively made to ourselves and to the rest of the country about what we are going to do.''

To be sure, such communication works both ways. Obama backers used the Web to let him know how angry they were that he voted for legislation overhauling U.S. electronic spying and providing immunity for telecommunications companies that aided government wiretapping without warrants.

Just as outside groups that oppose abortion or support stronger environmental protection use their membership to push their concerns, Obama could use his mailing list to prod Congress to keep his priorities atop the agenda.

As Ed Lasky points out, there are other uses for this list also; intimidating enemies:

Imagine the type of campaign that faced critics of Barack Obama on the Milt Rosenberg show-multiplied by a huge magnitude. They would clog Congressmen’s lines-computer and phone lines.

Ronald Reagan would famously "go over the heads of Congress" and directly address the American people, asking them to write their legislator and urge them to enact his programs. It worked magnificently and Democrats hated him for it.

But Reagan's efforts took place at a time when there were basically only three broadcast networks who were almost forced to carry his oval office addresses. Today, that strategy wouldn't work quite as well with the glut of cable channels and a news media more reticent about putting the President on the air unless his speech is going to be "newsworthy.

Obama's huge army of supporters - plugged in and able to be activated by hitting "enter" on a computer - represents a threat to free speech if Obama were to choose to use it to silence critics. Given what we've seen already, it seems logical that this will be one use of the email list that Obama will employ early and often.