AndyInTheCloud.com – Andy Fawcett is the CTO of Financial Force and his blog contains great Salesforce Developer content because he’s constantly pushing the boundaries of the Force.com platform. He’s also a significant contributor to the Salesforce community with great tools like the Declarative Lookup Rollup Summary and the Apex Metadata API Framework.
salesforceblogs.com – Oliver Hansen is a Salesforce consultant at 7dots.eu. His blog contains a compilation of many Salesforce blogs, learning and career resources, and other useful information. The SalesforceBlogs.com 360 degree Master Feed aggregates various posts from around the web and has a lot of great content.
sfdc99.com – David Liu is a Salesforce Technical Architect at Google. He started in Marketing. His site shows non-coding Admins and others how to get started coding with Salesforce.
His Coding Challenges are a fun way to test your knowledge and see how others implement the solution. Check out my Account Rivals solution from my October 11, 2014 comment. Unfortunately, the code formatting gets stripped out.