I have already said that I love DZone, but I want to say more - I was really happy to discover another lovely feature of DZone - Refcardz. Refcardz are basically reference cards on development topics available to download for free for DZone members, if you are not a DZone member, then you can register for free.

The reference card are in PDF and ready to be printed. They must be kept near your desk because if you need a quick reference, Refcardz will always help you. I believe the Refcardz on jQuery Selectors and Windows PowerShell will be useful for many people.

The current Refcardz are mostly on Java, RIA and AJAX, as well as on the general programming principles.

General programming principles:

• Design Patterns

Java:

• Groovy
• NetBeans
• GlassFish Application Server
• IntelliJ IDEA
• Dependency Injection in EJB 3
• Spring Configuration
• GWT Style, Configuration and JSNI Reference
• Getting Started with Eclipse (it's useful not only for Java developers)

RIA:

• Getting Started with AJAX
• jQuery Selectors
• Silverlight 2
• Flexible Rails: Flex 3 on Rails 2

Windows PowerShell:

• Windows PowerShell

XML:

• RSS and Atom

They are planning to publish more refcardz, you can subscribe to get notified.