Chris Brogan inspired me to think about online communities and “platform fatigue.” In a post aimed at public relations pros, he says:

“We want to connect on maybe two or three networks tops. One or two of these will remain the “commons” services like Facebook or Twitter. The rest of people’s interactions are going to fall into smaller communities, often private or self-selected in some way.”

Our time, attention span and dedication are limited. How much can we spare for a new online community if we’re already spending time on Facebook, Twitter and other sites?

Think about your usual online haunts. Where do you spend time? How do you get there? Do you have to make an effort to go there or does it come to you? It makes a difference when a community isn’t yet a habit.

My homepage is Google Reader. That’s where I start my online day, reading and visiting blogs to comment. I generally return to it for more reading later if I get my work done.

I use Hootsuite to visit Twitter once or twice a day, unless I’m taking a day off. While on Twitter I chat, click links and open tabs to read later. Twitter is my most valuable professional and personal hangout, well worth the time spent there.

I dip into Facebook about once a day to read and comment. Ok, ok, sometimes more than once a day if it’s the weekend. Like many, Facebook is more of a personal hangout.

I scan LinkedIn network updates and questions in my Reader and get my group discussions delivered by email. I don’t go to the LI site unless I’m changing my status or commenting on something. Could I live without LinkedIn? Definitely, and I may change my habits, but I feel strangely compelled to have a presence there, for now.

Isn’t that enough online action? It is for me. If you’re hoping to get my participation in yet another community or social platform, you’ve got a challenge on your hands. My time, brain and heart are already stretched too thin. If you want to play with me, you’ll have to come to one of my playgrounds — blogs, Twitter, Facebook — unless you deliver value, packaged efficiently, that I can’t get anywhere else. But considering the value I already get from my existing networks, that’s a stretch. Do you feel the same way?

However, an online community might be a good stepping stone for people who aren’t yet immersed in social media like I am. Again, only if it provides value they can’t get anywhere else in real life. Sometimes the key to attracting and retaining new members is an old-fashioned remedy — local face-to-face events. Those real life experiences make it easier for social media newbies to deepen their relationships with other community members and with the community itself.

Brogan tells brand managers to settle for “small bites” – small communities. Focus on the quality of the interactions, not the quantity of members. A quality experience leads to member loyalty and word-of-mouth marketing.

I agree there’s a place for small or niche communities, but it might be 3rd or 4th place unless they provide unparalleled value or one-stop shopping plus value. I’d love a niche community where I could do it all — check my Twitter stream, read and comment on blogs, and see Facebook or LinkedIn updates. If I can do that and get to know and learn from others in my niche – be they writers, association professionals, frugal home cooks or craft beer geeks – then you might have a potential resident.

How about you? Are you a member of any niche online communities? What is it about that community that makes you find time to spend there?