Here are some sites that contain quality articles and content:
The Server Side - Contains great articles, forums and reviews. Good source for pattern ideas.
Martin Fowler - Martin Fowler is a smart fellow and manages to write his ideas in an easy to digest format. His website contains many great articles about OO including refactoring, patterns and methodologies.
Agile Data - Scott Ambler’s website containing a lot of useful articles, many referring to Agile methods.