Why are there so many NoSQL databases?
nawroth: To answer your question I think things will settle down -- in the long run it's too hard for developers to deal with all the alternatives and their differences.
To get a high-level overview of the NOSQL space you could read this blog entry: http://blogs.neotechnology.com/emil/2009/11/nosql-scaling-to... As Ben Scofield puts it (cited in that post): "NoSQL DBs often provide better substrates for modeling business domains". I think this aspect is often forgotten in the debate. So I'd say: start from your business domain, what are the characteristics of it? Then look for a DBMS that is a good fit. And to get down to the details of some of the NOSQL systems, here's a walk through: http://www.vineetgupta.com/2010/01/nosql-databases-part-1-la...