Blogs are a great way to work out your ideas, document your workflow for yourself and others, and share interesting discoveries with the community. They make great portfolio pieces to gain recognition in your industry, as well as time capsules of a particular point and perspective in your life.
I write design and development articles on my design firm's blog, Stay Regular. I also run a cannabis based publication and blog + vlog to educate readers about the intricacies and reality of the world of weed.