For my current side project, which I've been working on for a year (and is probably a month or two away from being "beta-able"), I've learned Clojure, Elasticsearch, ES6, mithril.js, Ansible, and have expanded/refined my skills with RabbitMQ, Postgres (or SQL in general), and distributed architecture (not to mention getting to figure out how systemd service and timer configuration files work).
I've really been working hard on it because my current day job doesn't involve any programming, and by the time I get home in the evening I'm really jonesing for some code.
Have my side projects made me a better developer? Without a doubt. Am I any more employable? No, not really - I still haven't figured out how to improve my 'Cultural Fit' via side projects.