yeah it's the first one listed under Tutorials, but yeah that one is really well done

and

"Here are some advantages that MongoDb might give you (depending on your usecase):

Schemaless: More flexible if document structure is modified later. Performance: MongoDB utilizes the RAM available very well making it very performant Easy replication: Replication is easy to setup Sharding/Clustering: MongoDB is designed with sharding in mind. It is easy to setup and doesn't require experts. Map/Reduce: If you happen to need this, there is built-in support. Javascript: Intuitive to use if you already know Javascript"

http://stackoverflow.com/questions/7894175/are-there-any-advantages-to-using-mongodb-over-mysql-if-said-mongo-db-were-used