FORTUNE — Scott McNealy can barely conceal his enthusiasm as he sits down in the media room of his Silicon Valley mansion to watch the New Hampshire Republican presidential debate. But it is not the debate itself that has Sun Microsystems’ longtime CEO literally on the edge of his seat — in fact, his enormous television is actually on “mute.”

No, he is pumped because two of the six candidates on the screen are using Wayin, an online polling startup that McNealy co-founded with a financier friend, to measure their supporters’ opinions and to gauge their performances in the early January debate. Mitt Romney and Newt Gingrich both use Wayin, as does the Republican National Committee and Frank Luntz, the Republican strategist and pollster. “I’m flat-out excited,” McNealy says. “I’m investing an enormous amount of my waking hours in this.”

Nearly 30 years after he co-founded Sun, and two years after the company sold to Oracle (ORCL), one of the tech industry’s most outspoken and colorful executives is back. Only instead of selling servers and software to businesses, he’s trying to get consumers, sports teams, and corporations — and politicians — to embrace a social media tool that’s a little hard to define: It is part polling app, part interactive media tool (think Twitter), and part enterprise service.

The polling software at the heart of Wayin is super easy to use. It allows you to create basic questionnaires, on the web or using a mobile app, by selecting an image and asking a question. Pick a photo of the Fab Four, ask Who is your favorite Beatle?, and bingo, the answers from your followers will start trickling in immediately.

Launched in October, the service has gotten early traction in politics. Romney — the candidate McNealy favors, by the way — has used Wayin to ask his supporters on Facebook what the most important issue in the election is. (Some 42% say the economy.) Pollster Luntz, who is a Wayin investor, went on The Sean Hannity Show after the Fox News debate in December and asked viewers to vote on who had won. Within 10 minutes he had 5,000 responses (early on, viewers had Gingrich winning, but sentiment gradually shifted to Ron Paul). “There are times when polling overnight isn’t fast enough,” Luntz says.

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The campaigns’ use of Wayin underscores the rising importance of social media in politics. “We are trying to reach across as many platforms as possible,” says Kathryn Wheeler, the national Facebook director for the Gingrich campaign. “The younger generation likes this newer, faster, more visual platform,” she says about Wayin. (While Wayin’s major political users are all Republicans, as is McNealy, the company says it has pitched itself to the Obama camp — which wholeheartedly embraced social media in 2008 — but has not heard back.)

McNealy, who serves as executive chairman, foresees many other uses. Online fashion magazines could use Wayin to poll readers on a new purse, and consumer goods companies could use it to test new packaging ideas. A retailer like Wal-Mart (WMT) could poll employees on how their week went to determine which stores have morale problems, he says. And Wayin could also play a role in interactive television: AT&T (T) has built Wayin into its U-verse broadband television service, so if you are watching the NFL playoffs, for example, the Wayin app on your phone will automatically suggest related polls. (Will the Bulls win in overtime? Will they make the playoffs this year?)

Wayin has raised $6.5 million from McNealy and other investors, and McNealy is furiously working his Rolodex to get his former big-iron customers to give it a go. Revenue will come from advertising and sales to companies who may want to use the service to measure customer satisfaction or employee sentiment.

The biggest challenge for Wayin may be getting heard above the noise. Facebook already has a built-in questions app, and upstarts like Qriously and PollDaddy offer ways to gauge opinions in real time. Services like Yahoo’s IntoNow (YHOO) and GetGlue allow users to interact alongside television programs. During the New Hampshire debate, ABC News was encouraging its viewers to weigh in — not with Wayin, but with Twitter by using the hashtag #nhdebate. Twitter may not have the tools to classify the answers as neatly as Wayin, but it does have more than 100 million users.

This article is from the February 6, 2012 issue of Fortune.