I've been looking att different web stacks, mainly rails and node.js. One thing that strikes me is that while rails is often used with a relational database Node.js seem to go hand in hand with Mongodb, judging by the blogosphere.
Is there a specific reason for this? I like the modularity of node but I'm also sceptical to NOSQL. I get the feeling that if having a rdbms is important I should use rails since they seem to be a second class citizen in the node ecosystem.