http://pragprog.com/book/rwdata/seven-databases-in-seven-weeks
^ I picked this up a few months ago. They review seven data-stores and although I think they are quite fair in how they go about it you can tell the authors greatly favor couchdb. they even made a song for the book with couchdb in it: http://www.youtube.com/watch?v=bSAc56YCOaE the chapter on polyglot persistence really helped me personally, I hope someone here finds it interesting. No I don't work for the authors. -G
