There are a couple:

A system that updates user accounts to connect them into our wifi system by parsing thousands of processing files written in Clojure. The project was short lived and mainly experimental, It has complete test cases and the jar generated from it is still purring silently on the main application. It was used to replace an $85k vendor application that made no fucking sense. The code has not been touched in 2 years and the jar is still there. The dba mentioned the solution to the vendor, the vendor tried buying it from me, but being that it belongs to the institution nothing was touched, still, it got the VP's attention that I can make programs that would be bought for that level, it caught his attention even more when I showed him the codebase and he recognized a Lisp variant (he is old, and was back in the day a Fortran and Cobol developer)

A small Python categorical ML program that determines certain attributes of user generated data and effectively places them on the proper categories on the main DB. The program generates estimates of the users and the predictions have a 95% correctness rate. The DBA still needs to double check the generated results before doing the db updates. I don't remember how I coded it because I was mostly drunk when I experiment on the scenario. It also got the attention of the VP and director since the web tech manager was apparently doing crazy ML shit that they were not expecting me to do, it made them paranoid that I would eventually leave for a ML role somewhere, still here, but I want more moneys!!

A program that generates PDF documentation from user data, written in Go, Python and Perl (yes Perl) I even got shit from the lead developer since I used languages outside of their current scope of work. Dude had no option but to follow along with it :P since I am his boss

Many more. I am normally proud of my work code. But my biggest moment is my current ntural language processing unit that I am trying to code for my home, but I don't have enough power to build it with my computers, currently, my AI is too stupid, but sometimes it does reply back to my commands and does the things I ask it to do (simple things, opening a browser, search for a song etc) but 7 times out of ten it wont work :P