The Dirty Dozen of Application Development Mistakes
InfoWorld's Peter Wayner wrote a story about what he thinks are the 12 most common programming mistakes and how to avoid them.
Wayner talks about "playing it fast and loose" with user submitted data and writing sloppy code that contains lots of null values.
He takes programmers to task for not writing modular code and for relying too much on frameworks that can obscure problems.
So for a refresher on what not to do, check Wayner's list.