DZone is a community-driven website where software developers can post links to articles and reviews. There’s other great content there, but I want to focus on the huge collection of free reference cards they offer in PDF format.  Some of their recent titles are:

• Agile Adoption: Reducing Cost
• Effective Process Modeling with BPM & BPMN
• Flex & Spring Integration
• Apache Maven 2
• Getting Started with Equinox and OSGi

The reason I like this concept so much because my specialty is having no specialty.  I have a very diverse set of skills.  But when you know so many languages and technologies that have a lot of common (Meet the new language, same as the old language), it’s great to have quick reference materials to refresh myself on the ins and outs of the hat I need to wear that day, or to an interview the next day.  The quality of the material is high, too.