We use Lua as our primary scripting language for third party developers - it's fast, the runtime can be quite small and fits into everywhere it needs to go - from mobile to web.
We utilise PHP in a number of places - particularly third party software such as our forums.
Heavily used in front-end client scripting and backend infrastructure; we've been progressively migrating all our infrastructure to be written in C#/.NET Core.
High-speed update-aware storage used in our region server infrastructure; provides a good middle layer for storage of rapidly modified information.
Reliable inter-service messaging with failover and error routing. Used heavily in backend infrastructure for long-lived tasks.