Backups: As we're using MySQL databases and Percona Xtrabackup to backup these, I've created some Python scripts to automate the backup/storage steps: github.com/deviantony/xtrabackup-scripts
Backup validation: How to check that the backup archive we created is valid? Well, I've created a tool that leverages Docker to create ephemeral containers in which a backup restoration can occur: github.com/deviantony/valigator
Automation of the server provisioning / configuration process using Puppet (puppetlabs.com) and Foreman (theforeman.org), this allowed us to easily and quickly deploy new servers
Also a lot of processes manually done before in the company, replaced by bash scripts or command lines triggered/scheduled by Rundeck (rundeck.org)