If you've been meaning to check out one or more of these databases, these tutorials could form the basis for a good weekend project.
How to Move from MySQL to CouchDB: Part 1
If you're interested in migrating a MySQL database to CouchDB, or just want to learn more about how CouchDB works in comparison to a SQL database, check out this tutorial from the CouchOne blog:
If you have a database built using MySQL, you might be wondering if, and more importantly how, that database (and your application) can be moved to CouchDB. The biggest stumbling block is not the technical aspects of creating the CouchDB or storing your information (although they are important), instead it's about looking at your data in a different way, and then knowing how that changes how your application works.
We're going to start by looking at how you can turn your MySQL database structure into CouchDB, and how querying your database in CouchDB differs from the methods used in MySQL.
MongoDB: Basic Queries
Above is a video tutorial on basic MongoDB queries from ThinkVitamin. There are other videos in this series, but you'll have to sign up for a ThinkVitamin membership.
Introduction to Amazon's SimpleDB
Amazon.com has a somewhat overlooked NoSQL database called SimpleDB. As Tom Borthwick points out in his tutorial, there's more "no" than just NoSQL: "No datatypes (except utf-8 strings), no transactions, no joins, no indexes, no schema, no administration, and no cost for minimal usage."