pgloader (Dimitri Fontaine) is a great piece of software.

There's also cl-abnf from the same author and project which is another great example of the expressive power of common lisp.

Also, everything Fernando Boretti does is awesome ;)

https://github.com/eudoxia0 http://eudoxia.me/article/common-lisp-sotu-2015/ https://github.com/dimitri/cl-abnf