A generic intro to NoSQL by Ben Scofield.
The slides go quickly (as it’s normal for an intro presentation) through probably the most representative NoSQL solutions: Redis, Tokyo Cabinet, Cassandra, CouchDB, MongoDB, Riak, Neo4j.
What I have found more interesting is the following categorization:
|Key-Value stores||high||high||high||none||variable (none)|
|Document stores||high||variable (high)||high||low||variable (low)|
|Graph databases||variable||variable||high||high||graph theory|
|Relational databases||variable||variable||low||moderate||relational algebra|
Another way to look at the above categorization is in this slide from the (awesome) presentation on graphs and Neo4j by Emil Eifrem