Here's a couple great links...
StoryFix - A new series of posts on characters has just started. And be sure to check out the series on story structure.
KillZone - This is a post by James Scott Bell on writing action scenes.
Lawrence Block on Writing This is such a good post. Even if you don't write mysteries, there is a great message for every writer.
The Seven Habits of Highly Effective Writers - How many do you have?
Steps to Plotting a Thriller
When a Scene Isn't Working