By now, virtually any organization that is committed to the web has asked: how can social media and online community strengthen our relationship to our members or customers, and help us fulfill our mission?

That is fundamentally the same question that a handful of organizations were starting to ask five years ago, when Rob and I first started Social Signal. But the context for that question has completely changed. Five years ago there was no Twitter, YouTube was a brand-new, unknown startup, and Facebook had only just opened its network to high school students. Organizations that built online communities for their members, customers or the public were typically convening a group of people who couldn’t connect otherwise, or hosting a conversation that wouldn’t otherwise take place.

At the time, we advised organizations that they had a unique, limited time opportunity to launch their online conversations. We pointed out that the growth of online communities meant that users were starting to make their commitments to specific sites or networks; get in early, and yours could be one of the primary networks with which your audience engaged.

That window closed two or three years ago: an organization that creates an online community today is mostly competing for attention with its members’ or customers’ pre-existing commitments to Facebook, Twitter, Flickr, LinkedIn and YouTube. Organizations that built niche communities before these sites took off have in some cases been able to retain their most passionate members, but it’s now hard to find members with that kind of passion for a new community: the kinds of people who can get worked up about participating in online communities have already joined several (or many!) and are busy blogging, commenting or posting on the ones they already belong to. Even if you meet those members where they are, by creating a Facebook page or a Twitter profile, it can be hard to get their attention.

Yet a great many businesses, non-profits and government agencies are still coming to the social web, with the party well underway. They want to tap into the power of online conversation for building relationships with customers, members or citizens; to access social networks as a way of getting a message out; to strengthen their brand and reputation with online content, especially the user-contributed kind that carries the greatest credibility. They’ve got fewer resources to work with as they enter the social web, and face tougher competitive pressures than the early entrants.

But there is a half-full glass at the end of the tunnel outside the social media window that has now closed. Sure, in 2010 it’s a lot harder to attract members to YAFSN (Yet Another F***ing Social Network). But it is a lot easier to explain your social media efforts to your board, staff, customers or members: the odds are good that most of them already use some kind of social media tool, so they’ll understand the intuition behind your social media efforts and find it that much easier to start using whatever you create, because it will feel familiar.

Something else is easier too: figuring out what to do. In five years of working with socially-minded businesses, government agencies and not-for-profits, we’ve discovered some consistent patterns in what’s feasible and effective for organizations under constraint. There are two types of constraint that typically shape how organizations engage with the social web: the size of their budget, and the size of their potential audience.

I’ve drafted a series of blog posts that walk organizations through the process of developing a social media strategy while facing budget or audience constraints. This approach is shaped by the 90-9-1 rule, which tells us that it’s very hard for an organization with a limited audience to achieve a self-sustaining volume of user-generated content; and by the 80/20 rule, which tells us that it’s crazy for an organization to spend tens of thousands of dollars on a social media strategy when their limited audience means they’re likely to end up with one of two basic approaches. I figure that most organizations can get 80% of the way towards a solid social media presence by following one of these two approaches, and that only a small number will have the resources to develop the innovative concept or high-octane engagement strategy that gets them to 100%.

You can call this approach the Rule of 84: 80/20 + 90-9-1. It’s intended to save a lot of time, money and wasted effort on the part of organizations — mostly nonprofits, but also some businesses — who would otherwise take the Field of Dreams approach to social media: if we build it, they will come. For most organizations, if you build it, they won’t come: they’re too busy on Twitter, Facebook, or YouTube. Follow this strategy and you’ll be able to create an effective social media presence that is robust in the face of low participation or a limited budget.