There are a number of blogs that I follow dedicated to the Salesforce ecosystem. Not every one of these is code-focused, but they've all taught me a number of things. In no particular order, here are a few to get you started:
http://www.codefriar.com—OK, shameless plug here; this one is my blog. I mostly talk about Salesforce and mobile development.
http://www.adminhero.com/—Brent Downey spends his blog time helping readers understand how to get the most out of your Salesforce org. While Brent doesn't do much with code, his blog is invaluable when it comes to mastering the declarative aspects of the Salesforce ecosystem.
http://andyinthecloud.com/—Andrew Fawcett's blog is the gold standard for code-based Salesforce blogs. He's ...