Best Alternative Professional Option

It’s exactly what Nicholas Bate was writing about in the ‘new career mindset’ series, and here is a blog entry by Seth Godin encouraging professionals to develop multiple skills.
Why? To have options. Because when you have the options, ‘not only does your confidence change, your work does as well’.

I would love to broaden my horizon, and would welcome your ideas. So tell me, what are your alternative skills? Or what skill set and knowledge do you see would be a good idea to learn about and develop in today’s world?