Motley Fool, the profitable but distinctly Web 1.0 publisher for stock pickers, has got a new secret weapon as of today: CAPS, a free social stock ranking application that the Fools are confident will return them to new media hotness and hyper-growth.

In the spirit of social sites such as Digg or the recent hit sports betting site PicksPal, CAPS allows users to vote on the future performance of specific stocks. Users predict whether they think a given equity will outperform - or underperform - the S&P 500 index within the time frame they choose. The site then aggregates the forecasts into a single score, using a five star scale, for each stock. Users are also scored based upon their track record over time: the better their stock calls, the more their vote counts in the stock rankings.

People are overwhelmed by the sheer volume of divergent stock opinions, argues David Gardner, who, along with brother Tom, founded Motley Fool 14 years ago. Gardner was brimming over with excitement on a visit to The Browser's Fortune offices last week, and noted in particular that CAPS will also include stock ratings by pro analysts thanks to a deal with Briefing.com. That means the application will rank the pros against each other, and against the unwashed public, using a common scale. Thus, he said, all those slightly divergent terms such as "overweight" and "outperform" will be "translated into a lingua franca."

Moreover, Gardner believes that opening up voting to a broad audience will mean better coverage of the "long tail" of equities. "Fifty percent of stocks are covered by two analysts or less," he noted.

As revolutionary as Gardner hopes his new service will be, the WSJ reports that CAPS comes at a time when a number of other firms are experimenting with new stock-picking tools. Notable among them are Charles Schwab and E*Trade.

Still, The Browser is impressed by CAPs. It builds smartly on the site's years of experience with web community. The big unknown here, as it is elsewhere in Web 2.0-land, is motivation: what will provoke users over time to contribute rankings?

Gardner says he isn't worried: "If you have any competitive blood in your body, you'll be hooked." Hmm. More reassuring are hints from the Fools folks that they've come up with at least six tentative schemes for compensating users for their opinions.

And there is at least one clearly promising sign that this dog will hunt. One small Colorado research boutique has asked the Fools to include in CAPS some of its stock picks that were not carried on the Briefing.com feed. In other words, far from being upset that their picks were being aggregated, some analysts see CAPS as free marketing. Watch out First Call.