CouchDB fills an important niche between embedded databases, like SQLlite and Distributed NoSQL solutions, like riak. Also it's seems to be targeting once popular "Mobile/Offline Databases" sector (it was before 3G and even GPRS took off and when wireless bandwidth was limited and not always on (i.e. dial up).
I think about CouchDB as a modern version of MS-Access and/or Lotus Notes ;-)
