1. Scripting out a team. I've built a collection of bash scripts to do what one of our teams does. Except the script does it in 30min and always does it well where that team used to take 4 to 10 hours and almost always missed something in the way.

2. Automate 70-80% of our BAU tasks with a single >4k loc bash script. Integrations with servicenow, lots of internal portals, predefined huge sets of commands to run on separate servers or lists of servers, do all sorts of diagnostics, schedule hw maintenance for DC folks, chase for approvals, track CHNG/CTSK tickets in a graphical chart so we would not miss any of them and lots lots more.
Finally we were able to afford time to make some coffee/tea.

These are the bau optimizations I'm proud of the most. And they have made significant impact on how our teams operate.

Whoever recognizes both company values in the tags and know what is that company - are they still using ´S´ in unix team? :)