Benefits from reading the "Programming Dashboard Widgets" book

• Learn how to create Dashboard Widgets
  
• Demystify Dashboard Widgets
  
• Debug Dashboard Widgets
  
• Learn useful tools
  

You will also learn:

• the basics of MySQL
  
• the basics of Shell programming
  
• some UNIX topics
  

Every chapter has a rich Bibliography based on the presented topic.

My opinion is that by reading the eBook you will become a better Mac OS X user and programmer.

The eBook describes how you can create Apple Dashboard Widgets using many programming languages including JavaScript, Perl, Objective-C, and PHP. You can buy it here.