At work:

• geometric computations in a Performance-sensitive optimization algorithm that was drafted in Python. After confirmation, the whole algorithm was rewritten to C++, which was fine since it was part of a large science experiment
• rewriting / wrapping some middleware + APIs so that other people can transition new work to rust. The resulting interfaces turned out very pleasant to use!

At home:

• building command-line software for my Gemini PDA. This is an ARM device and Rust is far easier to cross-compile than C++.
• Implementing a larger optimization & solver algorithm (a few thousand lines) which I coded some time ago in Clojure. Very easy to parallize.