Postgres started as a Lisp program, and turned out to be too difficult to develop in a mix of C and Lisp.

The Objectstore database was developed by former Lispers, who wrote an earlier object-oriented database in Lisp.

+1 for mentioning my friend Denny. I wrote an application that Experteliigence sold for me - lots of fun. Expertelligence had a high talent density.