Caravel Content Management: Caravel is a content management system with the somewhat odd implementation of storing everything in LDAP, rather than a traditional SQL database. I don’t know of any other system that does this.
This project was open-sourced from a system used to power 2,000 Mennonite churches. See the Wikipedia page.
Ironically, Joe and I had a discussion about this very thing last week. It’s actually a natural fit — LDAP has a very flexible schema with a naturally hierarchical storage scheme.
I don’t know enough about LDAP to play with it, but I enjoy innovative ways of doing anything.