Should Every Business Invest in Social Media?

I was taking the shuttle bus from an off-site airport parking lot this week when I noticed a large poster on the window of the bus. "Like Us on Facebook! Tweet Us on Twitter! Watch Us on YouTube!" it beseeched travelers. Really? Will someone please tell these people that they're running a parking lot?

I'm not a snarky person, but I watch companies pant, like a dog chasing a truck, to have a big presence on social media, seemingly without pondering whether it's a good investment for them.