The document discusses different types of NoSQL databases including key-value stores, Bigtable clones, document databases, and graph and triple stores. Key-value stores are useful for caching and allow fast retrieval of data through a single key. Bigtable clones are suited for sparse data and work well with Hadoop. Document databases are useful for unstructured data. Graph and triple stores are well-suited for representing relationships and social graphs. The document provides examples of products for each type and tips for using them.