The absolute most important part of collective action is the collective. At the same time, it the the most difficult and unpredictable piece of such an effort. For many otherwise good ideas, the lack of a crowd deals a critical blow to their success.

In collecting a crowd, one should consider the incentives that motivate that crowd. However, collecting a crowd in not the only way to gain one. What I’m talking about is repurposing a crowd.

While obviously not an option for everybody, repurposing a crowd offers, in many cases, the best chances for crowdsourced success. This may entail piggybacking functions onto your widely-used product (especially useful if you’re Google or Yahoo—which most of us aren’t) but it can also mean borrowing from somebody else’s (like with Facebook platform). The point comes down to this: it’s hard to provide incentive for users to frequent a new site in their online routine, but it is much easier to utilize the sites that they’re already visiting for other purposes.

Here are three directions to consider.

1. Making an audience into participants

Sometimes you have to make do with what you have. When you’re a local radio station competing with a television network, “what you have” can seem frustratingly limited. When it comes to traffic reporting, the difference may be that the big guys have helicopters in the sky and cameras on busy road. How can you compete with that?

For radio stations, the answer lies in what they do have: an audience actively experiencing the traffic. What has emerged from is traffic reporting based on mobile phone audience tips. This crowdsourced model helps narrow the competitive gap that expensive technologies create.

The magic lies in the clever mobilization of readers. There is already a large, dormant audience armed with the information that a traffic watch needs. Giving that audience a voice is all that is needed to get the information. A similar example is Are You Being Gauged from WNYC.

2. Crowdsource as a feature, not as the main event

Some of the most useful examples of crowdsourcing in the wild formed on the backs of other products. The golden standard here is the tagging feature of Flickr. Users have no rules forced upon them on how to encde their information. They just want to put up their photos, and tagging is something that is simply offered for them to stay organized. However, on the larger scale, all the users that do end up using tags helps create an extremely semantically relevant corpus of images (and, as I’ve mentioned before, the first place you should go when looking for images).

Returning to the earlier example of traffic information, such “incidental crowdsourcing” is being tested in using cellphone tower information to determine how fast traffic is moving. Simply by having one’s cellphone in their cupholder, they’re contributing data. Similar to this are e-commerce recommendation engines, where simply by surfing a site, a user contributes to an algorithm for predicting what similar users would want.

3. Reimagine Popular Actions

In this form of repurposing crowds, the question come down to how one can squeeze extra juice out of something already being used. his is the approach that Luis von Ahn projects take, especially well epitomized in reCaptcha and the ESP Game. If people are already using captchas, why not have them also digitize scanned texts? If people like to relax with an online game, why not also have them encode image metadata?

Before starting a crowd-assisted project, don’t bet on people finding their way to it. Think about how existing groups and communities can be used and you’re much more likely to succeed.