It's worth noting that the current crop of NoSQL databases isn't _that_ old, and many of these sites were designed and built years before mongo or riak were rea

It's worth noting that the current crop of NoSQL databases isn't _that_ old, and many of these sites were designed and built years before mongo or riak were really production ready. I'd bet that in 3-5 years this list will have more nontraditional databases on it.