I never wrote about my development experiences until I started working here at Hashrocket, but it's something I would highly encourage developers at any level to start doing, for a few reasons:
When you have to write down what you're doing and explain it, you go to extra lengths to really understand what you're talking about out of fear of embarrassing yourself in front of your piers. I remember in detail everything I've blogged about, but I can't remember what I ate for breakfast, or the method signature for collection_select. I'd bet that if I blogged about collect_select, I'd never have to look at those docs again.
Everyone in the open source community have benefitted from the blog posts, packages, frameworks, and tutorials created by other developers. You may not have the time to write your own package, or regularly commit to an open source project, but you can contribute by blogging.
A few days ago, I started a personal project. Inspired by Hashrocket's TIL, a collection of mini blogs where rocketeers write about something they learned that day, I decided to blog my daily experiences as I go. The project will start as a test driven Ember app with a mock API, then I'll build the Phoenix API. It won't be a very complex app, but there will be lots of testing, some web scrapping, and probably some PDF parsing, which means I have to trudge through the depths of the JVM using either Clojure or JRuby. Follow along in the blog folder of my repo.