MongoDB is a widely used, general-purpose database. It is open-source, written in C++, and document-oriented. MongoDB has a strong support for MapReduce and uses BSON (Binary JSON) format for storage purposes. MongoDB supports different languages with a wide range of drivers.
The latest releases can be downloaded from mongodb.org.
The mailing list is very busy and almost every question on earth has been asked on there, so try searching the archives. (Searching Google with "site:groups.google.com/group/mongodb-user" generally works better than using the Google Groups search bar.)
Some relational-styled features
- Secondary Indexes
- Range Queries
RDBMS terms and their MongoDB equivilent
- Row - Document
- Table - Collection (Group of Documents)