The main focus of these notes is the relational model. There is a lot of interest at the moment though in NoSQL database ("Not Only SQL"). There are several different kinds of NoSQL database - unlike relational database, there is no standard approach which can make things confusing. In general, NoSQL databases tend to support better scaling and better integration with object-oriented programing languages. They do however give up on some of the guarantees of consistency that relational databases offer.
Check out some of the links in the sidebar for more information on some key topics. Please note though that if you want to become proficient with NoSQL you need to a) decide which model you will go with, and b) spend a long time practising. NoSQL is not a free lunch. Like any other technological choice, you should choose the right kind of database for your project rather than deciding from the outset that the relational mode is dead and NoSQL is the future.
The NoSQLzoo site offers a similar set of exercise to SQLzoo using MongoDB. Just click through and get started...