I overheard this recently: "I got a Pinterest invitation the other day, and it took me by surprise because I can't even remember the last time I even logged on to Pinterest!" If this person was in your target audience and you were investing a good amount of time building up your Pinterest channel, wouldn't this statement concern you?

One of the biggest social media strategy challenges these days is simply figuring out into which channels and platforms to invest your time and resources. It might feel like every month another new social media platform launches that you need to know about. Pick the right channel early on and you could hit the jackpot--achieve early success, have your case study featured on all kinds of media outlets, attract more followers/fans/friends from all the free PR and have social media talents knocking on your door for a job. Pick a channel that never gets off the ground or after it's peaked, and it could be you and the crickets at your next social media ROI analysis meeting.

Here's a cautionary tale from three former social heavy hitters--which may now be in their twilight.

Take for a moment another former social media darling: Groupon. Groupon's model relied heavily on social networks and social sharing in order to get the critical mass required for one of their limited-time deals to be released. Consumers and deal seekers loved Groupon (and still pretty much do), but the small businesses Groupon went after often couldn't afford these deals: Many businesses didn't retain those one-time, deal-redeeming customers and forfeited much of their profit in the process of attracting Groupon customers.

We all know what happened next: Copycats entered the market, diluting Groupon's power. After a shaky IPO and the recent ousting of its founder and CEO, Groupon is struggling to re-group. It may have a retained part of its audience, but finding merchants willing to discount their products through Groupon will be a challenge.

Pinterest has had different sorts of challenges.  For a time, it too was the darling of social media news and power users, and it quickly found its way into the marketing mix for companies that use imagery to sell. In many ways, Pinterest has built its business right--including developing a stream of revenue early on. But it was just too easy for users to lose interest. I came, I pinned, I conquered--now what?  Once you've created a pinboard of your fantasy vacation, room designs, automobiles you'll never own, just how frequently are you logging on to Pinterest? And without the critical mass of audience, how much time should a marketer put into building out their Pinterest channel? Pinterest recently launched a redesign and analytics features, but will these be enough to rebuild its former momentum?

And then there's foursquare. When foursquare launched, there was huge novelty in its mainstay check-in feature with users vying to become the "mayor" of a location based on the frequency of their check-ins. Foursquare's popularity among local businesses looking to raise their visibility and cool factor grew, and so did its place in social media plans. These days, however, you can check-in from almost any social media platform, so the big dogs Facebook and Twitter have eclipsed foursquare.

Abandon Ship?

What does this mean to those of you with accounts and marketing programs with these networks? I am not advising you to abandon ship altogether, but consider your rationale for continuing to support your accounts. If these platforms truly provide you with value-- real revenues, audience engagement or even business intelligence--by all means, keep up the great work. On the other hand, if all they really are at this point is a resource drain, cut your losses now and move onto something else or point these resources towards other channels that really help you meet your goals.