I watched this presentation which is really inspiring, by Damien Katz who developed a database using Erlang(a functional language).He talks about the circumstances and hardships he had while developing a new db even there are others in industry which has become integral part of infrastructure.Cool people make cool stuffs !!
What so interesting about CouchDB ?
More about CouchDB http://couchdb.apache.org/docs/intro.html
Applications using CouchDB http://wiki.apache.org/couchdb/CouchDB_in_the_wild