At 9:38 this morning, the Obama campaign sent out an urgent e-mail seeking help in making one million calls to voters before 3 P.M. All you had to do was log in to his website, click on a battleground state of your choice, and obtain a call list. At 11:55 A.M., the McCain campaign did something similar but made it even easier: they simply placed the names and phone numbers of 10 Floridians into the body of an e-mail, together with a short script.

These are only the most visible signs of a vast 11th-hour effort to leverage the Web to influence voters on an unprecedented scale. And it will help decide this election. "It's hard to even describe the difference it is making today. It is the greatest get-out-the-vote effort in American history, all because these guys are able to mash the old operations with technology--everything from Google Maps to online tools--to help reach voters," says Joe Trippi, who was campaign manager for Howard Dean in 2004, when he broke ground in using online campaigning tools. "It's pretty amazing. It's come a long way in four years."

In similar fashion, massive shoe-leather door-knocking efforts are under way, also organized on large scale through the candidates' websites. Volunteers have been able to sign up to visit battleground states, obtaining maps, lists of people to visit, and scripts to follow. Generally, the targets are people registered with the candidate's party but who have had spotty voting records.

In the past two days, Obama e-mails claimed that the online calling tools enabled 500,000 calls on Sunday alone, and 600,000 on Monday. McCain's entreaties made no numerical claims. It's likely that Obama is outgunning his opponent, having aggressively built an online network of supporters and their e-mail addresses--and having developed strategies to connect them with each other and with campaign tasks--since he became a candidate in early 2007. The McCain camp overhauled its social and Web tools several months ago. "They are doing the same stuff, but with a much smaller network. Obama has been growing virally for two years. And the first mover has a huge advantage," Trippi observes.

The possibilities are many. At the simplest level, they start with voter lists and get known supporters to call them and take notes (using Web-based tools) on the outcomes. Then the campaign can revamp the lists for follow-ups as appropriate. But public databases allow myriad ways to slice and dice voter lists for more custom pitches that are made far easier via the Web. For example, the Obama campaign could, in theory, cross-reference voter lists with lists of people who hold hunting licenses, and then have hunter supporters call that group to tell them Obama won't disarm them. Or they could use demographic information from census data to make general guesses about the income bracket of the voter based on where he or she lives and make pitches about proposed tax policies. All of this becomes vastly easier on the Web: matching the right callers with the right targets, getting things done quickly, and keeping accurate records of it all.

Beyond what the campaigns are offering, some nonpartisan efforts are also leveraging technology to aid in the get-out-the-vote effort. For example, Mobile Commons, a startup in New York City, is offering a way to find your polling place by simply text-messaging your home address and zip code. Let's say you live at Tech Review headquarters, One Main Street, in Cambridge, MA, 02142. You text "pp 1 Main 02142 69866" and then get out and vote.