CL can be used pretty much anywhere nowadays, even on the web with ECL wasm compilation.

An extensible LLM agent (such as https://pi.dev/ or maybe hermes) written in common lisp could be interesting. Conditions and restarts and general debugging and repair of the live system, fast startup, native execution speeds, ability to add or replace or modify core functionality on the fly, solid multi-threading support, dynamic introspection including documentation, CLOS and multiple dispatch, saved images.

I bet you do, or you will. In my case, I had been getting movie recommendations from friends and also randomly. I'd look up the flick on IMDB, metacritic, and rotten tomatoes and I'd guess whether I would like it.

I wanted something more 'algorithmic' - and more accurate.

So me and Claude build an sbcl-based Film Recommendation system. Type in a new film name, it goes to open film database OMDB, grabs the scores, and then, using films I have already rated and with a built-in tiny Neural Net, gives me a personal recommendation. It uses the OMDB data and an algo that weights those with my personal values (in half a dozen areas: overall, acting, cinematography, etc), along with a 'comments' box to note for friends / others.

The code is very well-done CL, heavily commented. The film & ratings database is stored as S-exprs, naturally, all in one file. I don't use a database as I only have a few hundred films, but maybe later I will. And that's the point -- this is a living chunk of code that I from time to time bolt in new features, or try new things (e.g. the UI is localhost:8080)

I fretted about having a 'real' project to really dig into CL for a long time, and finally, found a meaty-enough project that ends up being really useful & quite a learning (continuing learning) experience. I start it up inside emacs/sly like this:

  (ql:quickload '(:hunchentoot :dexador :yason))
  (load "s:/filmrec.lisp")
  (filmrec:start)

  (setf filmrec:*omdb-api-key* "fxxxx70")

  (filmrec:retrain)