It really depends on what you're storing and how you plan on interacting with it. If you don't need ad hoc queries CouchDB w/ defined views may work well. Other

It really depends on what you're storing and how you plan on interacting with it. If you don't need ad hoc queries CouchDB w/ defined views may work well. Otherwise consider another solution like mongo. If the available solutions are immature / undocumented feel free to contribute to them. That's what FOSS is all about ;)